利用GreenDAO可以非常方便的建立多張表之間的關聯
一對一關聯
通常我們在操作數據庫的時候，我們往往不是單獨的對一張表進行操作，而是對這張表的操作會聯動的影響另外一張表或者多張表，比如：現在有兩張表，一張是用戶User表（有name、age、sex三個字段），一張是頭像Picture表（有pictureId、pictureName、width、height四個字段）。假如用戶表和頭像表是一對一關係，一個用戶只有一個頭像，一個頭像只能有一個用戶，所以要建立這兩張表之間的聯繫，這兩張表肯定是需要關聯的，這樣就可以通過用戶的信息得到它的頭像信息。我們知道在數據庫中，關聯兩張表（暫且不說多對多關係的）一般都是把一張表的主鍵作爲另外一張表的外鍵來做的，所以在Android中也同樣，如果我們要關聯User表和Picture表，那麼只需要把Picture表的主鍵（假如是pictureId）作爲User表的外鍵即可，另外一個亦是如此，如： 
假設還是以上面的場景爲例，則利用GreenDAO建立User表和Picture表一對一的關聯可以這樣建立：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//把User表的主鍵name作爲Picture表的外鍵，把Picture的主鍵pictureId作爲User表的外鍵，這樣得到任何一個實體的信息都可以得到關聯的另外一個實體的信息
Property property = user<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"pictureId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getProperty</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
user<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToOne</span>(picture,property)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
Property propertyName = picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addStringProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getProperty</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToOne</span>(user,propertyName)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>
在爲Schema添加實體的時候，我們在相應的實體中添加另外一個表的主鍵即可：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"> Schema schema = new Schema(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"com.sunzxyong.greendao2"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
//User
Entity user = schema<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addEntity</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"User"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
user<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addStringProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.notNull</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.primaryKey</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
user<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addStringProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"sex"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
//Picture
Entity picture = schema<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addEntity</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Picture"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"pictureId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.primaryKey</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addStringProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"pictureName"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.notNull</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addIntProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"width"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addIntProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"height"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
//建立一對一關聯
Property property = user<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"pictureId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getProperty</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
user<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToOne</span>(picture,property)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
Property propertyName = picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addStringProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getProperty</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToOne</span>(user,propertyName)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
new DaoGenerator()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.generateAll</span>(schema, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"../GreenDAODemo/app/src/main/java-gen"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li></ul>
【注意】：目前多表關聯只能支持關聯的表只能有一個主鍵，所以我們不能加入user.addIdProperty();或者在表中設置了兩個主鍵，因爲user.addIdProperty();默認會把id作爲主鍵。所以當你的某張表存在與其它表關聯時，你需要檢查所關聯的那張表是否只設置了一個主鍵，否則將會報錯。
當右鍵運行生成相應的實體後，我們可以打開User類：
發現多了一個pictureId屬性，這正是User表的外鍵，Picture的主鍵，然後構造方法也需要我們傳入pictureId的值： 
User類中還提供了一個getPicture()方法，供我們直接得到當前User的Picture對象而得到相應信息，實際上它內部已經幫我們封裝好了相應的查詢方法，我們只需直接調用即可： 
同樣Picture類中也是這樣。
一對多關聯
大家都知道在超市購物時候，一位顧客可以有很多訂單，而一個訂單隻能屬於一位顧客，所以這就成了一對多的關係，假設顧客Customer表有customerId（primaryKey）、name兩個屬性，訂單Order表有orderId（primaryKey）、money兩個屬性。 
所以建立顧客和訂單之間的一對多關聯爲：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"> Schema schema = new Schema(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"com.sunzxyong.greendao3"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
//顧客
Entity customer = schema<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addEntity</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Customer"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
customer<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"customerId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.primaryKey</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
customer<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addStringProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.notNull</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
//訂單
Entity order = schema<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addEntity</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Order"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
order<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"orderId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.primaryKey</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
order<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addDoubleProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"money"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.notNull</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
//建立一對多關聯（顧客對訂單爲一對多）
Property property = order<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"customerId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getProperty</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
order<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToOne</span>(customer,property)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
customer<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToMany</span>(order,property)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setName</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"orders"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
new DaoGenerator()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.generateAll</span>(schema, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"../GreenDAODemo/app/src/main/java-gen"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li></ul>
當設置了顧客對訂單一對多關聯後，Order實體（和表）中會多一個屬性爲customerId，所以通過訂單我們可以得到該顧客信息，而Customer實體（和表）中會多一個List集合變量：List<Order>
orders，表示該顧客的所有訂單，其中orders其實是我們自定義的名字，在剛剛setName("orders")就是給這個變量設置了“orders“名稱，而Customer實體中還提供了一個方法getOrders()表示得到該顧客所有訂單：
<code class="hljs mathematica has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">List</span><<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">Order</span>> orders = customer.getOrders();</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>
事實上它也是封裝好了查詢Order中顧客id爲customerId的所有訂單。
多對多關聯
通常來說，在建立多對多關聯上，我們都會採用新建一張中間表，利用中間表把多對多這種複雜關係簡單化，在通常的選課系統上，一個學生可以選擇多門課，一門課可以被多個學生選，這就是多對多關係了，假設Student有studentId、name兩個屬性，Course有courseId、courseName兩個屬性，則建立多對多關係爲：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"> Schema schema = new Schema(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"com.sunzxyong.greendao4"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
//學生
Entity student = schema<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addEntity</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Student"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
student<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"studentId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.primaryKey</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
student<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addStringProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.notNull</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
//課程
Entity course = schema<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addEntity</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Course"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
course<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"courseId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.primaryKey</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
course<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addStringProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"courseName"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.notNull</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
//建立多對多關聯
Entity studentCourse = schema<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addEntity</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"StudentCourse"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
Property studentId = studentCourse<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"studentId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getProperty</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
Property courseId = studentCourse<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addLongProperty</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"courseId"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getProperty</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
studentCourse<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToOne</span>(student,studentId)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
studentCourse<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToOne</span>(course,courseId)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
student<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToMany</span>(studentCourse, studentId)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
course<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.addToMany</span>(studentCourse,courseId)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
new DaoGenerator()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.generateAll</span>(schema, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"../GreenDAODemo/app/src/main/java-gen"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li></ul>
這樣就建立學生和課程表多對多的關聯，學生實體和課程實體中都有這麼一個方法：
<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">public List<StudentCourse> getStudentCourseList(){
//<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>
意思就是得到一個StudentCourse的集合，而StudentCourse實體中又有這麼兩個方法：
<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"> public Student getStudent(){//<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>}
public Course getCourse(){//<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>
所以當我們得到了StudentCourse的List集合，我們可以通過StudentCourse中的這兩個方法來得到對應的學生或者課程信息。
轉自：http://blog.csdn.net/u010687392/article/details/48496299
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