从刚开始接触JSON 到现在差不多有两年时间了，最初接触JSON只知道是一种轻量级的数据交换格式。它基于JavaScript的一个子集。后来就很少用到了，后来开始使用Easyui ，就不得不跟Json打交道了。但是也一直没有整理过有关Json的相关知识。直到最近，在做一个项目，前台要求特别高，仅仅是easyui提供的方法已经没有办法满足需求，所以对jquery ,json ,又好好的使用了一次。这次让我收获很大。接下来就跟大家分享一下java中解析json的工具有哪些。
现在我知道了主要有三种：json-lib,jackson,fastjson。其中json-lib 算是比较早的了。这次项目中使用的也是json-lib ,先跟大家分享一下json-lib的使用。
具体的关于json-lib的知识不在赘述，简单的说json-lib 可以做什么，Json-lib可以将Java对象转成json格式的字符串，也可以将Java对象转换成xml格式的文档，同样可以将json字符串转换成Java对象或是将xml字符串转换成Java对象。
这里主要是用到了json的两个类：jsonObjec 和jsonArray 。
JSONObject是将Java对象转换成一个json的Object形式，JSONArray是将一个Java对象转换成json的Array格式。
那什么是json的Object形式、Array形式？
用通俗易懂的方法将，所谓的json的Object形式就是一个花括号里面存放的如JavaMap的键值对，如：{name:’hoojo’, age: 24}；
那么json的Array形式呢？
就是中括号，括起来的数组。如：[ ‘json’, true, 22]；
一、使用前提
首先要去官方下载json-lib工具包
下载地址：http://sourceforge.net/projects/json-lib/files/json-lib/json-lib-2.4/
目前最新的是2.4的版本，本示例中使用的是v2.3；json-lib还需要以下依赖包：
jakarta commons-lang 2.5
jakarta commons-beanutils 1.8.0
jakarta commons-collections 3.2.1
jakarta commons-logging 1.1.1
ezmorph 1.0.6
官方网址：http://json-lib.sourceforge.net/
然后将这些Jar拷贝到web-info 下的lib中。
二、javaBean
<span style="font-family:KaiTi_GB2312;font-size:18px;">@Entity
@Table(name = "job_content_detail")
public class JobContentDetail implements BaseEntity {
<span style="white-space:pre"> </span>@Id
@GeneratedValue(generator = "uuid")
@GenericGenerator(name = "uuid", strategy = "uuid.hex")
@Column(name = "ID", length = 32, nullable = false)
private String id;
@Column(name = "TS", length = 20, nullable = true)
private String ts;
@Column(name = "DR", length = 10, nullable = true)
private Integer dr;
@Column(name = "JOBCONTENTMAINID", length = 32, nullable = true)
private String jobcontentmainid;
@Column(name = "PRODUCTID", length = 32, nullable = true)
private String productid;
@Column(name = "PRODUCTUSAGE", length = 22, precision = 10, nullable = true)
private String productusage;
@Column(name = "ITEMQTY", length = 22, precision = 10, nullable = true)
private Double itemqty;
@Column(name = "BUILDERQTY", length = 22, precision = 10, nullable = true)
private Double builderqty;
@Column(name = "LABOURUNITID", length = 22, precision = 10, nullable = true)
private String labourunitid;
@Column(name = "LABOURFACTOR", length = 22, precision = 10, nullable = true)
private Double labourfactor;
@Column(name = "LABOURFACTOR2", length = 22, precision = 10, nullable = true)
private Double labourfactor2;
@Column(name = "LABOURFACTOR3", length = 22, precision = 10, nullable = true)
private Double labourfactor3;
@Column(name = "ManHours", length = 22, precision = 10, nullable = true)
private Double manhours;
@Column(name = "LabourRate", length = 22, precision = 10, nullable = true)
private Double labourrate;
@Column(name = "Total", length = 22, precision = 10, nullable = true)
private Double total;
@Column(name = "MATERIALUNITID", length = 32, nullable = true)
private String materialunitid;
@Column(name = "WASTEFACTOR", length = 22, precision = 10, nullable = true)
private Double wastefactor;
@Column(name = "MATERIALTOTAL", length = 22, precision = 10, nullable = true)
private Double materialtotal;
@Column(name = "MARERIALRATE", length = 22, precision = 10, nullable = true)
private Double marerialrate;
@Column(name = "MANUALLYKEYED", length = 2, nullable = true)
private String manuallykeyed;
@Column(name = "PRODUCTRATE", length = 22, precision = 10, nullable = true)
private Double productrate;
@Column(name = "PRODUCTMANUALENTRY", length = 150, nullable = true)
private String productmanualentry;
@Column(name = "LevelOfDifficulty", length = 22, precision = 10, nullable = true)
private Double levelofdifficulty;
@Column(name = "MATERIALQTY", length = 22, precision = 10, nullable = true)
private Double materialqty;
@Column(name = "MATERIALBUILDERQTY", length = 22, precision = 10, nullable = true)
private Double materialbuilderqty;
@Column(name = "MERCHANT1PRICE", length = 22, precision = 10, nullable = true)
private Double merchant1price;
@Column(name = "MERCHANT2PRICE", length = 22, precision = 10, nullable = true)
private Double merchant2price;
@Column(name = "MERCHANT3PRICE", length = 22, precision = 10, nullable = true)
private Double merchant3price;
@Column(name = "MERCHANT4PRICE", length = 22, precision = 10, nullable = true)
private Double merchant4price;
@Column(name = "MATERIALADJUSTMENT", length = 22, precision = 10, nullable = true)
private Double materialadjustment;
@Column(name = "SubContractorLabour", length = 2, nullable = true)
private String subcontractorlabour;
@Column(name = "SubContractorMaterial", length = 2, nullable = true)
private String subcontractormaterial;
@Column(name = "ProductName", length = 1000, nullable = true)
private String productname;
@Column(name="productcode",length=10,nullable=true)
private String productcode;
<span style="white-space:pre"> </span>//省略ge,set 方法，
}</span>三、JSON对象反序列化成java 对象/集合
使用json-lib 需要引入如下包：
<span style="font-family:KaiTi_GB2312;font-size:18px;">import net.sf.json.JSON;
import net.sf.json.JSONArray;
import net.sf.json.JSONFunction;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;
import net.sf.json.JsonConfig;
import net.sf.json.processors.JsonValueProcessor;
import net.sf.json.util.PropertyFilter;
import net.sf.json.xml.XMLSerializer;</span>1、将JSON字符串 转换成 javaObject
<span style="font-family:KaiTi_GB2312;font-size:18px;"><span style="white-space:pre"> </span>@Override
@RequestMapping("/save.do")
@ResponseBody
public Object save(HttpServletRequest request) {
//获取编辑数据 这里获取到的是json字符串
String inserted = request.getParameter("newRow");</span><span style="font-family:KaiTi_GB2312;font-size:18px;"><span style="white-space:pre"> </span>// 要转换的javabean
JobContentDetail detail = new JobContentDetail();</span><span style="font-family:KaiTi_GB2312;font-size:18px;"><span style="white-space:pre"> </span>//如果json 字符串不为空，就进行转化
if(inserted != null){
// 把string 转换成jsonObject
JSONObject jsonobj = JSONObject.fromObject(inserted); </span><span style="font-family:KaiTi_GB2312;font-size:18px;"><pre name="code" class="java" style="color: rgb(51, 51, 51); font-size: 14px; line-height: 21px;"><span style="white-space:pre"> </span>//把json字符串转换成对象<span style="font-family: 'Microsoft YaHei UI', 'Microsoft YaHei', SimSun, 'Segoe UI', Tahoma, Helvetica, sans-serif, 'Microsoft YaHei', Georgia, Helvetica, Arial, sans-serif, 宋体, PMingLiU, serif;"> </span></span>具体代码和jsonObject转换成javabean一样，唯独不同的是，转javabean使用的是tobean，转list使用的是 toCollection.
<span style="font-family:KaiTi_GB2312;font-size:18px;"><span style="white-space:pre"> </span>JSONArray array =JSONArray.fromObject(ens.toString());
@SuppressWarnings("unchecked")
List<JobContentDetail> listDetail=(List<JobContentDetail>)JSONArray.toCollection(array, JobContentDetail.class);</span>四、java 对象/集合序列化成json
个人感觉，将javaBean /list 转换成json比较容易。咱们一步一步来看代码，首先是测试的一些准备代码如下：
<span style="font-family:KaiTi_GB2312;font-size:18px;">@SuppressWarnings({ "deprecation", "unchecked" })
public class JsonlibTest {
private JSONArray jsonArray = null;
private JSONObject jsonObject = null;
private Student bean = null;
@Before
public void init() {
jsonArray = new JSONArray();
jsonObject = new JSONObject();
bean = new Student();
bean.setAddress("address");
bean.setEmail("email");
bean.setId(1);
bean.setName("haha");
Birthday day = new Birthday();
day.setBirthday("2010-11-22");
bean.setBirthday(day);
}
@After
public void destory() {
jsonArray = null;
jsonObject = null;
bean = null;
System.gc();
}
public final void fail(String string) {
System.out.println(string);
}
public final void failRed(String string) {
System.err.println(string);
}
}</span>开始正式我们的调用转换，
1、首先是javabean 转换成json ，
<span style="font-family:KaiTi_GB2312;font-size:18px;"> fail("==============Java Bean >>> JSON Object==================");
fail(JSONObject.fromObject(bean).toString());
fail("==============Java Bean >>> JSON Array==================");
fail(JSONArray.fromObject(bean).toString());//array会在最外层套上[]
fail("==============Java Bean >>> JSON Object ==================");
fail(JSONSerializer.toJSON(bean).toString());</span>==============Java Bean >>> JSON Object==================
{"address":"address","birthday":{"birthday":"2010-11-22"},"email":"email","id":1,"name":"haha"}
==============Java Bean >>> JSON Array==================
[{"address":"address","birthday":{"birthday":"2010-11-22"},"email":"email","id":1,"name":"haha"}]
==============Java Bean >>> JSON Object ==================
{"address":"address","birthday":{"birthday":"2010-11-22"},"email":"email","id":1,"name":"haha"}
2、javalist 转换成json
<span style="font-family:KaiTi_GB2312;font-size:18px;">@Test
public void writeList2JSON() {
fail("==============Java List >>> JSON Array==================");
List<Student> stu = new ArrayList<Student>();
stu.add(bean);
bean.setName("jack");
stu.add(bean);
fail(JSONArray.fromObject(stu).toString());
fail(JSONSerializer.toJSON(stu).toString());
}</span>
==============Java List >>> JSON Array==================
[{"address":"address","birthday":{"birthday":"2010-11-22"},"email":"email","id":1,"name":"jack"},
{"address":"address","birthday":{"birthday":"2010-11-22"},"email":"email","id":1,"name":"jack"}]
[{"address":"address","birthday":{"birthday":"2010-11-22"},"email":"email","id":1,"name":"jack"},
{"address":"address","birthday":{"birthday":"2010-11-22"},"email":"email","id":1,"name":"jack"}]
如果仔细看代码，会发现一个现象，在javabean转换成json对象的时候，我们也可以使用jsonarray将javaben转换成 jsonarray 。并不是说转换成jsonarray的必须是一个list，它可以是一个kjavabean.
如果你是转换List集合，一定得用JSONArray或是JSONSrializer提供的序列化方法。如果你用JSONObject.fromObject方法转换List会出现异常，通常使用JSONSrializer这个JSON序列化的方法，它会自动识别你传递的对象的类型，然后转换成相应的JSON字符串。
json-lib 还可以进行xml 和 javabean之间的转化，但是我还没有使用到，具体内容参考: