Android學習（50） -- 使用post方式提交數據

要點

post提交數據是用流寫給服務器的

協議頭中多了兩個屬性

Content-Type: application/x-www-form-urlencoded，描述提交的數據的mimetype
Content-Length: 30，描述提交的數據的長度

//給請求頭添加post多出來的兩個屬性
String data = "name=" + URLEncoder.encode(name) + "&pass=" + pass;
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
conn.setRequestProperty("Content-Length", data.length() + "");

設置允許打開post請求的流

conn.setDoOutput(true);

獲取連接對象的輸出流，往流裡寫要提交給服務器的數據

OutputStream os = conn.getOutputStream();
os.write(data.getBytes());

核心代碼

public class MainActivity extends Activity {

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

	Handler handler = new Handler(){
		public void handleMessage(android.os.Message msg) {
			Toast.makeText(MainActivity.this, (String)msg.obj, 0).show();
		}
	};
	
	public void click(View v){
		EditText et_name = (EditText) findViewById(R.id.et_name);
		EditText et_pass = (EditText) findViewById(R.id.et_pass);
		
		final String name = et_name.getText().toString();
		final String pass = et_pass.getText().toString();
		
		Thread t = new Thread(){
			@Override
			public void run() {
				//提交的數據需要經過url編碼，英文和數字編碼後不變
				@SuppressWarnings("deprecation")
				String path = "http://192.168.13.13/Web2/servlet/LoginServlet";
				
				try {
					URL url = new URL(path);
					HttpURLConnection conn = (HttpURLConnection) url.openConnection();
					conn.setRequestMethod("POST");
					conn.setConnectTimeout(5000);
					conn.setReadTimeout(5000);
					
					//拼接出要提交的數據的字符串
					String data = "name=" + URLEncoder.encode(name) + "&pass=" + pass;
					//添加post請求的兩行屬性
					conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
					conn.setRequestProperty("Content-Length", data.length() + "");
					
					//設置打開輸出流
					conn.setDoOutput(true);
					//拿到輸出流
					OutputStream os = conn.getOutputStream();
					//使用輸出流往服務器提交數據
					os.write(data.getBytes());
					if(conn.getResponseCode() == 200){
						InputStream is = conn.getInputStream();
						String text = Utils.getTextFromStream(is);
						
						Message msg = handler.obtainMessage();
						msg.obj = text;
						handler.sendMessage(msg);
					}
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		};
		t.start();
		
		
		
	}

}

getTextFromStream

	public static String getTextFromStream(InputStream is){
		
		byte[] b = new byte[1024];
		int len = 0;
		//創建字節數組輸出流，讀取輸入流的文本數據時，同步把數據寫入數組輸出流
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		try {
			while((len = is.read(b)) != -1){
				bos.write(b, 0, len);
			}
			//把字節數組輸出流裡的數據轉換成字節數組
			String text = new String(bos.toByteArray());
			return text;
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
	}