Android（java）学习笔记203：网页源码查看器（Handler消息机制）

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity" >

<EditText
android:id="@+id/et_path"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="http://192.168.1.100:8080/hello.jsp" />

<Button
android:onClick="click"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="查看源码" />

<ScrollView
android:layout_width="fill_parent"
android:layout_height="fill_parent" >

<TextView
android:id="@+id/tv_result"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</ScrollView>

</LinearLayout>

 package com.itheima.netsourceviewer;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.itheima.netsourceviewer.utils.StreamTools;

public class MainActivity extends Activity {
protected static final int SUCCESS = 1;
protected static final int ERROR = 2;

private EditText et_path;
private TextView tv_result;

private Handler handler = new Handler(){
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case SUCCESS:
String text = (String) msg.obj;
tv_result.setText(text);
break;
case ERROR:
Toast.makeText(MainActivity.this, "请求失败", 1).show();
break;
}
};
};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_path = (EditText) findViewById(R.id.et_path);
tv_result = (TextView) findViewById(R.id.tv_result);
}
/**
* 查看源文件的点击事件
* @param view
*/
public void click(View view){
final String path = et_path.getText().toString().trim();
//访问网络，把html源文件下载下来
new Thread(){
public void run() {
try {
//获取url对象
URL url = new URL(path);
//获取链接对象
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
//获取请求方式，默认GET
conn.setRequestMethod("GET");//声明请求方式 默认get
//告诉服务器我是什么样的客户端
conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Linux; U; Android 2.3.3; zh-cn; sdk Build/GRI34) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1 MicroMessenger/6.0.0.57_r870003.501 NetType/internet");
//获取状态吗
int code = conn.getResponseCode();
//判断状态吗
if(code ==200){
InputStream is = conn.getInputStream();
//使用工具类， 把字节输入流的数据编程字符串
String result = StreamTools.readStream(is);

Message msg = Message.obtain();//减少消息创建的数量
msg.obj = result;
msg.what = SUCCESS;
handler.sendMessage(msg);
}
} catch (Exception e) {
Message msg = Message.obtain();//减少消息创建的数量
msg.what = ERROR;
handler.sendMessage(msg);
e.printStackTrace();
}
};
}.start();
}
}

 package com.itheima.netsourceviewer.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

/**
* 流的工具类
* @author Administrator
*
*/
public class StreamTools {
/**
* 把输入流的内容转换成字符串
* @param is
* @return null解析失败， string读取成功
*/
public static String readStream(InputStream is) {
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = -1;
while( (len = is.read(buffer))!=-1){
baos.write(buffer, 0, len);
}
is.close();
String temptext = new String(baos.toByteArray());
if(temptext.contains("charset=gb2312")){//解析meta标签
return new String(baos.toByteArray(),"gb2312");
}else{
return new String(baos.toByteArray(),"utf-8");
}
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
}