多維數組到JSON java/android gson

Question

在我的Web服務中，我正在查詢數據庫，並且想返回2列數據庫並將這些列放入2d數組中。

另外我想將數組轉換爲JSON併發送給客戶端。使用gson的客戶端在2d數組中解析來自服務器的消息。可能嗎？

我已經嘗試了很多，但至今沒有運氣。先謝謝你。

的最後一個版本我試過是這樣的：

private static String[][] db_load_mes (String u){ 
ArrayList<String> array1 = new ArrayList<String>(); 
ArrayList<String> array2 = new ArrayList<String>(); 
JSONObject messages = new JSONObject(); 
Connection c = null; 
    try{ 
    // Load the driver 
    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); 
    c = DriverManager.getConnection("jdbc:odbc:dsn1","mymsg","mymsg"); 
    Statement s = c.createStatement(); 

    // SQL code: 
    ResultSet r; 
    r = s.executeQuery("select * from accounts "); 

    int i = 0, j = 0; 
    int k = 0; 
    String x,y; 
    while(r.next()) { 
     x = r.getString("username"); 
     array1.add(x); 
     y = r.getString("password"); 
     array2.add(y); 

     k = k + 1; 
     } 

    int count = array1.size(); 
    String[][] row = new String[count][2]; 
     Iterator<String> iter = array1.iterator(); 
     while (iter.hasNext()) { 
      row[i][0]=iter.next(); 
      i++; 
     } 
     Iterator<String> iter2 = array2.iterator(); 
     while (iter2.hasNext()) { 
      row[j][1]=iter2.next();  
      j++; 
     } 
     for(int z=0;z<count;z++) 
     System.out.println(row[z][0] + "\t" + row[z][1] + "\n"); 


    if (k == 0) 
       System.err.println("no accounts!"); 

    c.close(); 
    s.close(); 


    } 
    catch(SQLException se) 
    { 
    System.err.println(se); 
    } catch (ClassNotFoundException e) { 
     e.printStackTrace(); 
    } 

    return ...; 
    } 

與上面的代碼我可以創建二維數組，但我怎麼能發送此陣給客戶端。

Answer 1

下面是我如何使用Gson從谷歌... 下載gson from here 將它包括在您的項目中。

package javaapplication1; 

import com.google.gson.Gson; 
import com.google.gson.GsonBuilder; 

public class JavaApplication1 { 

    public static void main(String[] args) { 

     int rows = 3; 
     String records[][] = new String[][]{{"bob", "123-pass"}, 
     {"erika", "abc123"}, 
     {"richard", "123123123"} 
     }; 

     Gson gson = new Gson(); 
     String recordsSerialized = gson.toJson(records); 

     System.out.println(recordsSerialized); 

     /* prints this   
     [["bob","123-pass"],["erika","abc123"],["richard","123123123"]]   
     */ 

     // if you want a better output import com.google.gson.GsonBuilder; 
     Gson gsonPretty = new GsonBuilder().setPrettyPrinting().create(); 
     String recordsSerializedPretty = gsonPretty.toJson(records); 
     System.out.println(recordsSerializedPretty); 
      /* PRINTS IN different lines.. I can't paste it here */ 

     // for retrieval 
     String retrievedArray[][] = gsonPretty.fromJson(recordsSerializedPretty, String[][].class); 

     for (int i = 0; i < retrievedArray.length; i++) { 
      for (int j = 0; j < retrievedArray[0].length; j++) { 
       System.out.print(retrievedArray[i][j]+" "); 
      } 
      System.out.println(""); 
     } 
     // PRINTS THIS 

     /* 
     bob 123-pass 
     erika abc123 
     richard 123123123 
     */ 
    } 

}