andLearning3練習

第三章的練習:聊天界面

新建project

首先我先畫了一個消息框的樣子png格式
我覺得還可以就這樣繼續吧。並放在了drawable下，命名爲message_text_view_left.png

先放到背景圖裏看一下，是不是特別醜。。。。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:background="@drawable/message_text_view_left"
    tools:context="com.example.wrjjrw.messageview.MainActivity">


</LinearLayout>

打開sdk目錄下tools文件，有一個draw9patch.bat文件,運行(需要配置jdk的環境變量),在導航欄中File然後打開剛剛的png.

在邊框繪製小黑點，然後可以拉伸，shift擦出。標記區域即可拉伸區域。然後替換原來的文件，發現超棒吧。。

ps水平翻轉一下，就都有了。//我好像命名錯了，不過不重要。

編寫聊天記錄。

build.gradle:

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.3.1'
    compile 'com.android.support:recyclerview-v7:25.3.1'
    testCompile 'junit:junit:4.12'
}

修改主界面。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#d8e0e8"
    tools:context="com.example.wrjjrw.messageview.MainActivity"
    >

    <android.support.v7.widget.RecyclerView
        android:id="@+id/msg_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_gravity="end"
        >

        <EditText
            android:id="@+id/input_text"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:hint="Type something here"
            android:maxLines = "2"
            />

        <Button
            android:id="@+id/send"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="發送"
            />

    </LinearLayout>


</LinearLayout>

中間顯示消息，下面消息框+發送消息。

新建Msg類。

public class Msg {

    public static final int TYPE_RECEIVED = 0;

    public static final int TYPE_SENT = 1;


    public String content;

    private int type;

    public Msg(String content, int type){
        this.content = content;
        this.type = type;
    }

    public int getType() {
        return type;
    }

    public String getContent() {
        return content;
    }
}

Alt+insert可以自動生成。get的東西。

收到是0，發送是1。

編寫子項佈局。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="10dp"
    >

    <LinearLayout
        android:id="@+id/left_layout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_gravity="left"
        android:background="@drawable/message_text_view_right"
        >
        <TextView
            android:id="@+id/left_msg"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_margin="10dp"
            android:textColor="#fff"
            />

    </LinearLayout>

    <LinearLayout
        android:id="@+id/right_layout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_gravity="right"
        android:background="@drawable/message_text_view_left"
        >

        <TextView
            android:id="@+id/right_msg"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_margin="10dp"
            android:textColor="#fff"
            />
    </LinearLayout>

</LinearLayout>

中間有些東西設反了，就將錯就錯了。

新建RecyclerView的適配器類，類名：MsgAdapter。

public class MsgAdapter extends RecyclerView.Adapter<MsgAdapter.ViewHolder> {

    private List<Msg>  mMsgList;

    static class ViewHolder extends RecyclerView.ViewHolder{
        LinearLayout leftLayout;
        LinearLayout rightLayout;

        TextView leftMsg;
        TextView rightMsg;

        public ViewHolder(View view){
            super(view);
            leftLayout = (LinearLayout) view.findViewById(R.id.left_layout);
            rightLayout = (LinearLayout) view.findViewById(R.id.right_layout);

            leftMsg = (TextView)leftLayout.findViewById(R.id.left_msg);
            rightMsg = (TextView)rightLayout.findViewById(R.id.right_msg);
        }

    }

    public MsgAdapter(List<Msg> msgList){
        mMsgList = msgList;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.msg_item,parent,false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Msg msg = mMsgList.get(position);
        if(msg.getType() == Msg.TYPE_RECEIVED){
            //receive the message
            holder.leftLayout.setVisibility(View.VISIBLE);
            holder.rightLayout.setVisibility(View.GONE);

            holder.leftMsg.setText(msg.getContent());
        }else if(msg.getType() == Msg.TYPE_SENT){
            //send the message
            holder.leftLayout.setVisibility(View.GONE);
            holder.rightLayout.setVisibility(View.VISIBLE);

            holder.rightMsg.setText(msg.getContent());
        }
    }

    @Override
    public int getItemCount() {
        return mMsgList.size();
    }
}

MainActivity：

public class MainActivity extends AppCompatActivity {

    private List<Msg> msgList = new ArrayList<>();

    private EditText inputText;

    private Button send;

    private RecyclerView msgRecyclerView;

    private MsgAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        inputText = (EditText) findViewById(R.id.input_text);
        send = (Button) findViewById(R.id.send);
        msgRecyclerView = (RecyclerView) findViewById(R.id.msg_recycler_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        msgRecyclerView.setLayoutManager(layoutManager);

        adapter = new MsgAdapter(msgList);
        msgRecyclerView.setAdapter(adapter);
        send.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                String content = inputText.getText().toString();

                if("".equals(content)){
                    Msg msg = new Msg(content, Msg.TYPE_SENT);
                    msgList.add(msg);
                    adapter.notifyItemInserted(msgList.size()-1);//receive a new message
                    //refresh
                    msgRecyclerView.scrollToPosition(msgList.size()-1);
                    inputText.setText("");

                }

            }
        });
    }
    private void initMsg(){
        Msg msg1 = new Msg("Hello guy!", Msg.TYPE_RECEIVED);
        msgList.add(msg1);

        Msg msg2 = new Msg("Hello,who is that", Msg.TYPE_SENT);
        msgList.add(msg2);

        Msg msg3 = new Msg("(ノ｀Д)ノ", Msg.TYPE_RECEIVED);
        msgList.add(msg3);
    }

}

沒有修改的代碼。初始化中初始了幾條數據。。。。

我自己給他設了一個隨機數，判斷是不是1，然後輸出哈哈哈。。。。雖然可能寫的比較低級，但還是要貼出來見證一下我的成長。

public class MainActivity extends AppCompatActivity {

    private List<Msg> msgList = new ArrayList<>();

    private EditText inputText;

    private Button send;

    private RecyclerView msgRecyclerView;

    private static int time = 0;

    private MsgAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        inputText = (EditText) findViewById(R.id.input_text);
        send = (Button) findViewById(R.id.send);
        msgRecyclerView = (RecyclerView) findViewById(R.id.msg_recycler_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        msgRecyclerView.setLayoutManager(layoutManager);

        adapter = new MsgAdapter(msgList);
        msgRecyclerView.setAdapter(adapter);
        send.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                String content = inputText.getText().toString();

                if(!"".equals(content)){
                    if(Msg.TYPE_SENT == 1){
                        time++;
                    }
                    Msg msg = new Msg(content, Msg.TYPE_SENT);
                    msgList.add(msg);
                    adapter.notifyItemInserted(msgList.size()-1);//a new message
                    //refresh
                    msgRecyclerView.scrollToPosition(msgList.size()-1);
                    inputText.setText("");

                    if(time>=(msgList.size() -1)/2){
                        Random random = new Random();
                        Msg msgReturn = new Msg(((random.nextInt(2) != 1)? "Yes":"no") ,Msg.TYPE_RECEIVED);


                        msgList.add(msgReturn);
                        adapter.notifyItemInserted(msgList.size()-1);//a new message
                        //refresh
                        msgRecyclerView.scrollToPosition(msgList.size()-1);

                    }

                }

            }
        });
    }

}