我想在listview中显示MySQL表数据，还必须在屏幕底部放置删除按钮。用户必须选择列表项，并通过单击删除按钮，应从mysql表和列表视图中删除特定数据。我可以正确显示记录，但无法从列表项中选择用户名字段。
查看用户活动
public class ViewUser extends AppCompatActivity implements View.OnClickListener {
private static final String VIEW_URL= "http://ajaygohel012.000webhostapp.com/ViewUser.php";
ListView listUser;
List<User> userlist;
private Button btnDelete;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_user);
listUser= findViewById(R.id.listUser);
userlist= new ArrayList<>();
btnDelete= (Button) findViewById(R.id.btnDelete);
final TextView viewUserName = (TextView) findViewById(R.id.viewUserName);
loadUserList();
listUser.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
listUser.setOnItemSelectedListener(this);
}
@Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
});
btnDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final String username = viewUserName.getText().toString();
Response.Listener<String> responseListener = new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONObject js = new JSONObject(response);
boolean success = js.getBoolean("success");
if (success){
finish();
startActivity(getIntent());
}
}catch(JSONException e){
e.printStackTrace();
}
}
};
DeleteRequest deleteRequest= new DeleteRequest(username, responseListener);
RequestQueue queue= Volley.newRequestQueue(ViewUser.this);
queue.add(deleteRequest);
}
});
}
private void loadUserList(){
final ProgressBar progressBar= (ProgressBar) findViewById(R.id.progressBar);
progressBar.setVisibility(View.VISIBLE);
StringRequest stringRequest= new StringRequest(Request.Method.GET, VIEW_URL, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
progressBar.setVisibility(View.INVISIBLE);
try {
JSONObject jsonObject= new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("data");
for (int i=0;jsonArray.length()>i;i++){
final JSONObject j= jsonArray.getJSONObject(i);
User user=new User();
String name = j.getString("name");
String empcode = j.getString("empcode");
String location = j.getString("location");
String department = j.getString("department");
String username = j.getString("username");
user.setName(name);
user.setEmpcode(empcode);
user.setLocation(location);
user.setDepartment(department);
user.setUsername(username);
userlist.add(user);
}
ListViewAdapter adapter = new ListViewAdapter(userlist, ViewUser.this);
listUser.setAdapter(adapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(ViewUser.this, error.getMessage(), Toast.LENGTH_SHORT);
}
});
RequestQueue requestQueue= Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
@Override
public void onClick(View view) {
if (view==btnDelete){
finish();
startActivity(new Intent(this, ViewUser.class));
}
}
}
DeleteRequest
class DeleteRequest extends StringRequest{
private static final String LOGIN_REQUEST_URL= "http://ajaygohel012.000webhostapp.com/DeleteUser.php";
private Map<String, String> params;
public DeleteRequest(String username, Response.Listener<String> listener) {
super(Request.Method.POST, LOGIN_REQUEST_URL, listener, null);
params = new HashMap<>();
params.put("username", username);
}
public Map<String, String> getParams(){
return params;
}
}
用户类
public class User {
String name, empcode, location, department, username;
public User(){
this.name=name;
this.empcode=empcode;
this.location=location;
this.department=department;
this.username=username;
}
public String getName() {
return name;
}
public String getEmpcode() {
return empcode;
}
public String getLocation() {
return location;
}
public String getDepartment() {
return department;
}
public String getUsername() {
return username;
}
public void setName(String name) {
this.name = name;
}
public void setEmpcode(String empcode) {
this.empcode = empcode;
}
public void setLocation(String location) {
this.location = location;
}
public void setDepartment(String department) {
this.department = department;
}
public void setUsername(String username) {
this.username = username;
}
}
ListViewAdapter
public class ListViewAdapter extends ArrayAdapter<User> {
private List<User> userlist;
private Context cntx;
public ListViewAdapter(List<User> userlist, Context cntx){
super(cntx, R.layout.list_item, userlist);
this.userlist=userlist;
this.cntx=cntx;
}
public View getView(int position, View convertView, ViewGroup parent){
LayoutInflater inflater= LayoutInflater.from(cntx);
View listViewitem= inflater.inflate(R.layout.list_item,null, true);
TextView viewName= listViewitem.findViewById(R.id.viewName);
TextView viewEmployeeCode= listViewitem.findViewById(R.id.viewEmployeeCode);
TextView viewLocation= listViewitem.findViewById(R.id.viewLocation);
TextView viewDepartment= listViewitem.findViewById(R.id.viewDepartment);
TextView viewUserName= listViewitem.findViewById(R.id.viewUserName);
User user=userlist.get(position);
viewName.setText(user.getName());
viewEmployeeCode.setText(user.getEmpcode());
viewLocation.setText(user.getLocation());
viewDepartment.setText(user.getDepartment());
viewUserName.setText(user.getUsername());
return listViewitem;
}
}
DeleteUser PHP
<?php
$connection = mysqli_connect("localhost", "abc", "xyz", "id3275958_user");
if(isset($_POST['username'])) {
$username = $_POST['username'];
$result = mysql_query("DELETE FROM user WHERE username = $username");
$response = array();
if (mysql_affected_rows() > 0) {
$response["success"] = 1;
$response["message"] = "User successfully deleted";
} else {
$response["success"] = 0;
$response["message"] = "No User found";
}
} else {
$response["success"] = 0;
$response["message"] = "Required field(s) is missing";
}
echo json_encode($response);
?>
我也制作了PHP脚本并给予我适当的回复。只想要从我的应用程序发送用户名仍然存在。
答案 0 :(得分：0)
你的代码工作得很好......
只想从我的应用中发送用户名。
我建议您btnDelete使用您的活动。
btnDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final String username = viewUserName.getText().toString();
Response.Listener<String> responseListener = new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONObject js = new JSONObject(response);
boolean success = js.getBoolean("success");
// TODO: you could add Response Here from your backend the remaining username
if (success){
finish();
startActivity(getIntent());
}
}catch(JSONException e){
e.printStackTrace();
}
...
}
});
与响应类似，然后显示或提示用户
username_count
String count = js.getString("username_count"); // Just convert into Int if you needed
答案 1 :(得分：0)
在PHP的这一行之后，您可以检查连接是否正常;
$connection = mysqli_connect("localhost", "abc", "xyz", "id3275958_user");
if(!$connection)
{ // creation of the connection object failed
die("connection object not created: ".mysqli_error($con));
}
if (mysqli_connect_errno())
{ // creation of the connection object has some other error
die("Connect failed: ".mysqli_connect_errno()." : ". mysqli_connect_error());
}
答案 2 :(得分：0)