Nine_Patch图片：一种被特殊处理过的图片，能够制定哪些区域可以被拉伸，哪些区域不可以
- 在Android Studio中使用.9图很简单：直接将图片名称以”.9.png”结束。
使用.9图必须注意一点：文件的后缀名必须是.9.png，不能是.png或者是.9.png.png，这样的命名都会导致编译失败。- 命名完成后双击图片即可进行编辑
点九图02.gif
第一步：创建项目导入图片
第二步：创建界面布局文件
注：这里因为用到RecyclerView所以要先天际啊RecyclerView相关库的依赖。
<?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="match_parent"
android:background="#d8e0e8"
>
<android.support.v7.widget.RecyclerView
android:id="@+id/msg_recycler_view"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1">
</android.support.v7.widget.RecyclerView>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="@+id/input_text"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_marginBottom="0dp"
android:hint="请输入信息"
android:maxLines="2"/>
<Button
android:id="@+id/send"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send"/>
</LinearLayout>
</LinearLayout>
第三步：创建信息窗口布局文件
<?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:layout_gravity="left"
android:background="@drawable/message_left">
<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:layout_gravity="right"
android:background="@drawable/message_right">
<TextView
android:id="@+id/right_msg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="10dp" />
</LinearLayout>
</LinearLayout>
第四步：创建信息实体类
package com.example.anwser_mac.uibestpractice;
/**
* Created by anwser_mac on 2017/4/1.
*/
public class Msg {
public static final int TYPE_RECEIVED = 0;
public static final int TYPE_SENT = 1;
private String content;
private int type;
public Msg(String content, int type) {
this.content = content;
this.type = type;
}
public String getContent() {
return content;
}
public int getType() {
return type;
}
}
第五步：自定义RecyclerView适配器
package com.example.anwser_mac.uibestpractice;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.util.List;
/**
* Created by anwser_mac on 2017/4/1.
*/
public class MsgAdapter extends RecyclerView.Adapter<MsgAdapter.Viewholder> {
private List<Msg> mMsgList;
static class Viewholder extends RecyclerView.ViewHolder {
android.widget.LinearLayout leftLayout;
android.widget.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) view.findViewById(R.id.left_msg);
rightMsg = (TextView) view.findViewById(R.id.right_msg);
}
}
public MsgAdapter(List<Msg> msgList) {
mMsgList = msgList;
}
@Override
public MsgAdapter.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(MsgAdapter.Viewholder holder, int position) {
Msg msg = mMsgList.get(position);
if (msg.getType() == Msg.TYPE_RECEIVED) {
//如果是收到的消息，则显示在左边的消息布局，将右边的消息布局隐藏
holder.leftLayout.setVisibility(View.VISIBLE);
holder.rightLayout.setVisibility(View.GONE);
holder.leftMsg.setText(msg.getContent());
} else if(msg.getType() == Msg.TYPE_SENT) {
//如果是发出的消息，则显示在右边的消息布局，将左边的消息布局隐藏
holder.rightLayout.setVisibility(View.VISIBLE);
holder.leftLayout.setVisibility(View.GONE);
holder.rightMsg.setText(msg.getContent());
}
}
@Override
public int getItemCount() {
return mMsgList.size();
}
}
第六步：加载数据
package com.example.anwser_mac.uibestpractice;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import java.util.ArrayList;
import java.util.List;
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.layout);
//初始化消息数据
initMsgs();
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);
//当有新消息时，刷新显示
adapter.notifyItemInserted(msgList.size()-1);
//定位到最后一行
msgRecyclerView.scrollToPosition(msgList.size()-1);
//清空输入框的内容
inputText.setText("");
}
}
});
}
private void initMsgs() {
Msg msg1 = new Msg("很高兴认识你", Msg.TYPE_RECEIVED);
msgList.add(msg1);
Msg msg2 = new Msg("你高兴得太早了", Msg.TYPE_SENT);
msgList.add(msg2);
Msg msg3 = new Msg("你丑开", Msg.TYPE_RECEIVED);
msgList.add(msg3);
}
}
点九图使用实例.gif
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