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我試圖從Android客戶端向HttpServlet發送一些數據。我的servlet代碼如下HttpServlet在Android客戶端的doPost（）中接收空值
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DBServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
Connection connection= null;
/**
* @see HttpServlet#HttpServlet()
*/
public DBServlet() {
super();
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
if(request.getParameterNames().hasMoreElements()){
insertRecord(request, getDbConnection());
}
else{ System.out.println("Servlet Started First Time"); }
}
/**
* Return database connection
* @return
*/
private Connection getDbConnection(){
String connectionURL = "jdbc:mysql://127.0.0.1:3306/testDB";
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(connectionURL, "root", "");
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return connection;
}
/**
* Insert record in database
* @param request
* @param connection
*/
private void insertRecord(HttpServletRequest request, Connection connection){
System.out.println("===== Received Record =====");
PreparedStatement stmt;
try {
stmt = connection.prepareStatement("insert into users(Name,email,password) values(?,?,?)");
stmt.setString(1, request.getParameter("name"));
stmt.setString(2, request.getParameter("e-mail"));
stmt.setString(3, request.getParameter("password"));
int i= stmt.executeUpdate();
if(i != 0){
System.out.println("data inserted !!!");
}
else{
System.out.println("data failed to insert");
}
} catch (SQLException e) {
e.printStackTrace();
}
finally{
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
和我的Android代碼
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import com.example.messenger.R;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.os.StrictMode;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class SignUp extends Activity {
Button register;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sign_up);
register = (Button)findViewById(R.id.register);
register.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.v("OnClick", "=== onClick ===");
registerUser();
}
});
}
@SuppressLint({ "NewApi", "NewApi", "NewApi" })
private void registerUser(){
String name= ((EditText)findViewById(R.id.name)).getText().toString();
String email= ((EditText)findViewById(R.id.email)).getText().toString();
String password= ((EditText)findViewById(R.id.password)).getText().toString();
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("name", name));
nameValuePairs.add(new BasicNameValuePair("email", email));
nameValuePairs.add(new BasicNameValuePair("password", password));
try {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
URL url=new URL("http://192.168.1.10:8080/DBservlet/DBServlet");
HttpURLConnection con = (HttpURLConnection)url.openConnection();
con.setDoOutput(true);
con.setRequestMethod("POST");
DataOutputStream dos=new DataOutputStream(con.getOutputStream());
dos.writeBytes(name);
dos.flush();
dos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
的問題是，當我運行「的Servlet」我得到的輸出「的Servlet開始第一次」，這是確定的，但在我運行我的android客戶端，並在EditText字段中寫入一些數據並按下注冊按鈕，沒有任何反應。 'Servlet'收不到任何東西。請讓我知道我該如何解決這個問題。
問候，
我不確定你具體*詢問*。你似乎已經做出了關於要求的觀察和陳述。我現在所能想到的只是，「好吧，只是相應地編寫代碼」。但那會使整個問題完全無用。請詳細說明具體問題。相應地編寫代碼時，你到底在哪裏？ – BalusC
我還不明白具體問題。只需放入一個'if'塊來檢查是否從客戶端收到數據，然後只在條件爲真時才執行查詢？如果實際上比這更復雜，那麼你真的需要詳細說明。我們不能神奇地照射到您的位置，以便自己查看您的代碼。編輯這個問題並加入一些清楚地表明問題的具體代碼對於更好地理解您的具體問題會非常有幫助。 – BalusC
您在編輯過程中添加的問題反過來很奇怪。保持'doPost（）'方法等待，直到請求屬性被設置？當前的線程基本上代表了HTTP請求本身時，這種情況如何呢？難道你不是真的指的是會話屬性嗎？也許你需要花更多的時間來學習基本的HTTP和servlet是如何工作的，然後再問概念錯誤的問題。這些帖子可能會有所幫助，然後：http://stackoverflow.com/a/3106909和http://stackoverflow.com/q/2793150一旦你正確掌握了基本概念，改善了這個問題。 – BalusC