Android 系列笔记 四

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handler 消息处理器：用于发送、接收消息

主线程中更新UI

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Handler handler=new Handler(){
	public void handleMessage(Message msg){
		super.handleMessage(msg);
		switch(msg.what){
			case SUCCESS:
				break;
			default:
				break
		}
	}
};

子线程向消息池发送消息

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new Thread(new Runnable(){
	public void run(){
		Message msg=new Message();
		msg.what=0;
		msg.obj=要操作的变量;
		handler.sendMessage(msg);
	}
}).start();

get请求

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HttpURLConnection conn = null;
try {
    Log.i("getPicture", address);
    URL url = new URL(address);
    conn = (HttpURLConnection) url.openConnection();
    conn.setConnectTimeout(10000);//设置请求超时时间
    conn.setReadTimeout(5000);//设置读取超时时间
    conn.setRequestMethod("GET");//设置请求类型
    conn.connect();
	
    int responseCode = conn.getResponseCode();//获取请求响应码
    if (responseCode == 200) {//请求成功
        Log.i("get picture", "loading......");
        Bitmap bitmap = BitmapFactory.decodeStream(conn.getInputStream());
        if(bitmap!=null) {
	       Message msg = new Message();//向主线程发送一条消息
	       msg.what = SUCCESS;
	       msg.obj = bitmap;
	       handler.sendMessage(msg);
        }else{
            Message msg = new Message();
            msg.what = ERROR;
            handler.sendMessage(msg);
        }
    } else {
        Log.i("error", "visit wrong");
    }
} catch (Exception e) {
    e.printStackTrace();
} finally {
    if (conn != null)
    	conn.disconnect();
}

图片缓存

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String urlString = "";
URL url = new URL(urlString);
HttpURLConnection connection = (HttpURLConnection)url.openConnection();
conn.setConnectTimeout(10000);//设置请求超时时间
conn.setReadTimeout(5000);//设置读取超时时间
conn.setRequestMethod("GET");//设置请求类型
conn.connect();
InputStream is = connection.getInputStream();
byte[] buffer = new byte[1024];
File file = new File(getCacheDir(), "");
FileOutputStream fos = new FileOutputStream(file);
int len = 0;
while((len = is.read(buffer)) != -1){
	fos.write(buffer, 0, len);
}
fos.close();

post请求

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new Thread(new Runnable(){
	public void run(){
		//执行网络操作
		runOnUiThread(new Runnable(){
			public void run(){
				//就是在主线程中执行操作
			    Toast.makeText(getApplicationContext(),"hello",Toast.LENGTH_SHORT).show();
				HttpURLConnection conn = null;
				try {
			        String address = "www.baidu.com";
				    URL url = new URL(address);
				    conn = (HttpURLConnection) url.openConnection();
				    conn.setConnectTimeout(10000);//设置请求超时时间
				    conn.setReadTimeout(5000);//设置读取超时时间
				    conn.setRequestMethod("POST");//设置请求类型
				        
				    String text = "username=" + name + "&password=" + password;
				    //设置post请求属性
				    conn.setRequestProperty("Content-Length", text.length() + "");
				    conn.setDoOutput(true);
				    OutputStream os = conn.getOutputStream();
				    os.write(text.getBytes());
				    conn.connect();

				    int responseCode = conn.getResponseCode();//获取请求响应码
				    if (responseCode == 200) {//请求成功
				        InputStream is = conn.getInputStream();
				        String info = Utils.getTextFromStream(is);				            
				    } else {
				        Log.i("error", "visit wrong");
				    }
				} catch (Exception e) {
				    e.printStackTrace();
				} finally {
				    if (conn != null)
				    	conn.disconnect();
				}
			}
		});
	}
});

编码问题

将汉字转为以%开头的字符串

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URLEncoder.encode(editText.getString(), "utf-8");

采用iso8859-1编码对姓名进行逆转，转成字节数组，再使用utf-8对数据编码

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username=new String(username.getBytes("iso8859-1"),"utf-8");