我正在开发一个 android 项目，我正在尝试获取用户在 EditText 框中输入的文本并将其添加到我服务器上的 SQL 表中。我认为问题出在没有正确的 SQL 查询，但我不确定我必须添加什么（当涉及到 SQL 时我一无所知）：S
当我在手机上运行这个应用程序时，它似乎承认我输入了一些内容并将其传递给数据库（没有出现错误或异常），但实际上没有任何内容添加到数据库表中。
任何关于我哪里出错的想法将不胜感激！
JDBC 服务器代码：
public class DBServlet4 extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/cs2001", "l2g0",
"l2g0");
stmt = con.createStatement();
stmt.executeUpdate("CREATE TABLE IF NOT EXISTS Students (id int, name varchar(45))");
stmt.executeUpdate("INSERT INTO Students (id, name) SELECT * FROM (SELECT '0', 'Michael') AS Temp WHERE NOT EXISTS (SELECT name FROM Students WHERE name = 'Michael') LIMIT 1");
//con.commit();
} catch (SQLException e) {
throw new ServletException(e.getMessage());
} catch (ClassNotFoundException e) {
throw new ServletException("JDBC Driver not found.", e);
} finally {
try {
if (rs != null) {
rs.close();
rs = null;
}
if (stmt != null) {
stmt.close();
stmt = null;
}
if (con != null) {
con.close();
con = null;
}
} catch (SQLException e) {
}
}
out.close();
}}
安卓代码：
public class MainActivity extends Activity{
private static final String ipAddress = "172.31.81.28";
private static final String portNumber = "8085";
protected TextView getText;
protected EditText inputName;
protected List<Student> students;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getText = (TextView) findViewById(R.id.select_output);
inputName = (EditText) findViewById(R.id.name_input);
}
public void onClick(View v)
{
switch (v.getId())
{
case R.id.post_button:
{
//
String responseString = "";
try
{
responseString = new HttpPostTask().execute("" + inputName.getText()).get(10, TimeUnit.SECONDS);
}
catch (InterruptedException e)
{
responseString = "#An Error Occured: InterruptedException";
e.printStackTrace();
}
catch (TimeoutException e)
{
responseString = "#An Error Occured: TimeoutException";
e.printStackTrace();
}
catch (ExecutionException e)
{
responseString = "#An Error Occured: ExecutionException";
e.printStackTrace();
}
if (responseString.startsWith("#"))
{
Toast.makeText(this,
responseString.substring(1), Toast.LENGTH_SHORT).show();
}
else
{
Toast.makeText(this,
responseString, Toast.LENGTH_SHORT).show();
}
break;
}
//code for getting data from DB
case R.id.get_button:
{
String responseString = "";
try
{
responseString = new HttpGetTask().execute("").get(10, TimeUnit.SECONDS);
}
catch (InterruptedException e)
{
responseString = "#An Error Occured: InterruptedException";
e.printStackTrace();
}
catch (TimeoutException e)
{
responseString = "#An Error Occured: TimeoutException";
e.printStackTrace();
}
catch (ExecutionException e)
{
responseString = "#An Error Occured: ExecutionException";
e.printStackTrace();
}
if (responseString.startsWith("#"))
{
Toast.makeText(this,
responseString.substring(1), Toast.LENGTH_SHORT).show();
}
else
{
Toast.makeText(this,
"Connection Successful", Toast.LENGTH_SHORT).show();
this.getText.setText(responseString);
this.students = parseData(responseString, "\n", ":");
int i = 0;
for (Student student : students)
{
++i;
System.out.print("[" + i + "] " + student + "\n");
}
}
break;
}
default:
{
/* Do Nothing */
}
}
}
private List<Student> parseData(String input, String caseDelimiter, String fieldDelimiter)
{
String[] temp = input.split(caseDelimiter);
LinkedList<Student> students = new LinkedList<Student>();
for (int i = 0; i < temp.length; i++)
{
String[] tempStudent = temp[i].split(fieldDelimiter);
students.add(new Student(Integer.parseInt(tempStudent[0]), tempStudent[1].trim()));
}
return students;
}
private class Student
{
int id;
String name;
public Student(int id, String name)
{
this.id = id;
this.name = name;
}
public String toString()
{
return "" + id + " - " + name;
}
}
private class HttpPostTask extends AsyncTask<String, Integer, String>
{
private static final String ipAddress = "172.31.81.28"; // *** UPDATE THIS ***
private static final String portNumber = "8085"; // *** UPDATE THIS ***
@Override
protected String doInBackground(String... args)
{
String responseString = "An Unknown Error Occured";
HttpParams params = new BasicHttpParams();
params.setParameter(CoreProtocolPNames.PROTOCOL_VERSION, HttpVersion.HTTP_1_1);
HttpClient client = new DefaultHttpClient(params);
String url = "http://" + ipAddress + ":" + portNumber + "/DB4";
HttpPost request = new HttpPost(url);
try
{
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("id", "123"));
nameValuePairs.add(new BasicNameValuePair("username", args[0]));
request.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = client.execute(request);
HttpEntity resEntityGet = response.getEntity();
if (resEntityGet != null)
{
responseString = EntityUtils.toString(resEntityGet);
}
}
catch (ClientProtocolException e)
{
responseString = "#An Error Occured: ClientProtocolException";
e.printStackTrace();
}
catch (IOException e)
{
responseString = "#An Error Occured: IOException";
e.printStackTrace();
}
return responseString;
}
}
private class HttpGetTask extends AsyncTask<String, Integer, String>
{
@Override
protected String doInBackground(String... args)
{
String url = "http://172.31.81.28:8085/DB4";
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(url);
String responseString = "";
try
{
HttpResponse response = client.execute(request);
HttpEntity resEntityGet = response.getEntity();
if (resEntityGet != null)
{
responseString = EntityUtils.toString(resEntityGet);
}
}
catch (Exception e)
{
responseString = "#An Error Occured: UndeclaredException";
e.printStackTrace();
}
return responseString;
}
}
}