一、网络保存数据介绍
可以使用网络来保存数据，在需要的时候从网络上获取数据，进而显示在App中。
用网络保存数据的方法有很多种，对于不同的网络数据采用不同的上传与获取方法。
本文利用LeanCloud来进行网络数据的存储。
LeanCloud是一种简单高效的数据和文件存储服务。感兴趣的可以查看网址：https://leancloud.cn/。关于LeanCloud的数据存储使用方法可以在里面找到，本文不讲述关于LeanCloud的使用，知识借助LeanCloud平台举一个在网络上存储数据的例子。
二、使用方法
1.上传数据
AVObject personObject = new AVObject(TABLENAME);
personObject.put(NAME, person.name);
personObject.put(AGE, person.age);
personObject.put(INFO, person.info);
personObject.saveInBackground(new SaveCallback() {
@Override
public void done(AVException e) {
if (e == null) {
Log.v(TAG, "put data success!");
} else {
Log.v(TAG, "put data failed!error:" + e.getMessage());
}
}
});
2. 读取数据
AVQuery<AVObject> avQuery = new AVQuery<>(TABLENAME);
avQuery.findInBackground(new FindCallback<AVObject>() {
@Override
public void done(List<AVObject> list, AVException e) {
if (e == null) {
Log.v(TAG, "get data success!");
String message = "";
for (int i = 0; i < list.size(); i++) {
String name = list.get(i).getString(NAME);
int age = list.get(i).getInt(AGE);
String info = list.get(i).getString(INFO); message += "name:" + name + ",age:" + age + ",info:" + info + ".\n";
}
textView.setText(message);
}
}
});
三、小案例
1.添加strings.xml文件
<string name="network">Network</string>
<string name="get_data">获取数据</string>
<string name="put_data">上传数据</string>
2.修改activity_main.xml文件
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.zhangmiao.datastoragedemo.MainActivity"> <LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"> <TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="@string/network" /> <LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="@dimen/fab_margin"
android:layout_marginTop="@dimen/fab_margin"
android:orientation="horizontal"> <Button
android:id="@+id/network_put"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/put_data" /> <Button
android:id="@+id/network_get"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/get_data" />
</LinearLayout> <TextView
android:id="@+id/table_info"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/app_name" />
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
3.添加NetworkDBManager类
package com.zhangmiao.datastoragedemo; import android.util.Log;
import android.widget.TextView; import com.avos.avoscloud.AVException;
import com.avos.avoscloud.AVObject;
import com.avos.avoscloud.AVQuery;
import com.avos.avoscloud.FindCallback;
import com.avos.avoscloud.SaveCallback; import java.util.List; /**
* Created by zhangmiao on 2016/12/22.
*/
public class NetworkDBManager { private static final String TAG = "NetworkDBManager"; private final static String TABLENAME = "person";
private final static String NAME = "name";
private final static String AGE = "age";
private final static String INFO = "info"; public void putData(Person person) {
AVObject personObject = new AVObject(TABLENAME);
personObject.put(NAME, person.name);
personObject.put(AGE, person.age);
personObject.put(INFO, person.info);
personObject.saveInBackground(new SaveCallback() {
@Override
public void done(AVException e) {
if (e == null) {
Log.v(TAG, "put data success!");
} else {
Log.v(TAG, "put data failed!error:" + e.getMessage());
}
}
});
} public void getData(final TextView textView) {
AVQuery<AVObject> avQuery = new AVQuery<>(TABLENAME);
avQuery.findInBackground(new FindCallback<AVObject>() {
@Override
public void done(List<AVObject> list, AVException e) {
if (e == null) {
Log.v(TAG, "get data success!");
String message = "";
for (int i = 0; i < list.size(); i++) {
String name = list.get(i).getString(NAME);
int age = list.get(i).getInt(AGE);
String info = list.get(i).getString(INFO); message += "name:" + name + ",age:" + age + ",info:" + info + ".\n";
}
textView.setText(message);
}
}
});
}
}
4.修改AndroidManifest.xml文件
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
5.修改MainActivity
package com.zhangmiao.datastoragedemo; import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.*;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView; import com.avos.avoscloud.AVOSCloud; import java.util.ArrayList;
import java.util.List; public class MainActivity extends AppCompatActivity implements View.OnClickListener {private NetworkDBManager mNetworkDBManager; private TextView mTableInfo; @Override
protected void onCreate(Bundle savedInstanceState) {
Log.v("MainActivity", "onCreate");
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); AVOSCloud.initialize(this, "yMNUazdBt872mNtC9aSakjYy-gzGzoHsz", "d4vw3VYdMCjLpsXRhHTBRutC");
mNetworkDBManager = new NetworkDBManager(); Button networkGet = (Button) findViewById(R.id.network_get);
Button networkPut = (Button) findViewById(R.id.network_put); mTableInfo = (TextView) findViewById(R.id.table_info); networkGet.setOnClickListener(this);
networkPut.setOnClickListener(this);
} @Override
public void onClick(View v) {
switch (v.getId()) {case R.id.network_put:
Person person3 = new Person("xiao", 23, "women");
Person person4 = new Person("zhao", 24, "men");
mNetworkDBManager.putData(person3);
mNetworkDBManager.putData(person4);
break;
case R.id.network_get:
mNetworkDBManager.getData(mTableInfo);
break;
default:
Log.v("MainActivity", "default");
break;
}
}
}