基于Java实现一个简单的单词本Android App的实践

目录

• 布局设计
• 代码
• AddDanciActivity.java
• DBOpenHelper.java

本文基于Java实现了一个简单的单词本安卓app，用的是SQLite数据库，包括布局文件、源码及实现图。

布局设计

单词本主界面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".AddDanciActivity">

    <EditText
        android:id="@+id/addword_edit"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:layout_marginTop="20dp"
        android:hint="单词:"
        android:textColor="@android:color/black"
        android:textColorHint="#DCDCDC"
        android:textSize="30dp" />

    <EditText
        android:id="@+id/fanyiword_edit"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:hint="解释:"
        android:textColor="@android:color/black"
        android:textColorHint="#DCDCDC"
        android:textSize="30dp" />

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentBottom = "true"
        android:layout_margin="5dp">
    <ListView
        android:id="@+id/add_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:textColor="@android:color/black"
        android:textColorHint="#DCDCDC"
        android:textSize="30dp"
        android:layout_above="@id/lineLayout"
        />

        <LinearLayout
            android:layout_height="50dp"
            android:layout_width="match_parent"
            android:id="@+id/lineLayout"
            android:layout_alignParentBottom="true"
            android:orientation="horizontal"
            android:gravity="center_horizontal"
            >
        <Button
            android:layout_width="100dp"
            android:layout_height="50dp"
            android:id="@+id/add_btn"
            android:text="添加" />
        <Button
            android:layout_width="100dp"
            android:layout_height="50dp"
            android:layout_centerHorizontal="true"
            android:id="@+id/shanchu_btn"
            android:layout_gravity="center_vertical"
            android:text="删除" />
        <Button
            android:layout_width="100dp"
            android:layout_height="50dp"
            android:id="@+id/quxiao_btn"
            android:layout_gravity="right"
            android:text="取消" />
        </LinearLayout>

    </RelativeLayout>

</LinearLayout>

代码

AddDanciActivity.java

单词本主界面的Activity

import androidx.appcompat.app.AppCompatActivity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

public class AddDanciActivity extends AppCompatActivity {

    private EditText wordedit;
    private EditText yisiedit;
    private Button add_btn;
    private Button quxiao_btn;
    private Button shanchu_btn;
    private ListView listview;
    private DBOpenHelper dbOpenHelper;//声明

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add_danci);
        dbOpenHelper = new DBOpenHelper(AddDanciActivity.this, "db_dict", null, 1);//实例化，创建数据库
        wordedit = (EditText) findViewById(R.id.addword_edit);
        yisiedit = (EditText) findViewById(R.id.fanyiword_edit);
        listview = (ListView) findViewById(R.id.add_list);
        add_btn = (Button) findViewById(R.id.add_btn);
        quxiao_btn = (Button) findViewById(R.id.quxiao_btn);
        shanchu_btn = (Button) findViewById(R.id.shanchu_btn);
        quxiao_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(AddDanciActivity.this, "返回单词本主界面", Toast.LENGTH_SHORT).show();
                finish();
            }
        });

        shanchu_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String word = wordedit.getText().toString();
                String ys = yisiedit.getText().toString();
                if (word.equals("")) {
                    Toast.makeText(AddDanciActivity.this, "填写的单词为空", Toast.LENGTH_SHORT).show();
                } else {
                    deleteData(dbOpenHelper.getReadableDatabase(), word);
                    Toast.makeText(AddDanciActivity.this, "删除成功", Toast.LENGTH_SHORT).show();
                }
            }
        });

        add_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String word = wordedit.getText().toString();
                String ys = yisiedit.getText().toString();
                if (word.equals("") || ys.equals("")) {
                    Toast.makeText(AddDanciActivity.this, "填写的单词或解释为空", Toast.LENGTH_SHORT).show();
                } else {
                    insertData(dbOpenHelper.getReadableDatabase(), word, ys);//插入生词
                    Toast.makeText(AddDanciActivity.this, "添加生词成功", Toast.LENGTH_SHORT).show();
                    renew();
                }
            }
        });
    }

    //插入数据的方法
    private void insertData(SQLiteDatabase sqLiteDatabase, String word, String ys) {
        ContentValues values = new ContentValues();
        values.put("word", word);//保存单词
        values.put("detail", ys);
        sqLiteDatabase.insert("tb_dict", null, values);//执行插入操作
        renew();
    }

    private void deleteData(SQLiteDatabase sqLiteDatabase, String word) {
        ContentValues values = new ContentValues();
        String[] args = {String.valueOf(word)};
        sqLiteDatabase.delete("tb_dict", "word=?", args);//执行删除操作
        renew();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (dbOpenHelper != null) {
            dbOpenHelper.close();//关闭
        }
    }

    public void renew() {
        Cursor cursor = dbOpenHelper.getReadableDatabase().query("tb_dict", null, null, null, null, null, null);
        ArrayList<Map<String, String>> resultList = new ArrayList<Map<String, String>>();
        while (cursor.moveToNext()) {
            Map<String, String> map = new HashMap<String, String>();
            map.put("word", cursor.getString(1));
            map.put("interpret", cursor.getString(2));
            resultList.add(map);
        }

        if (resultList == null || resultList.size() == 0) {
            Toast.makeText(AddDanciActivity.this, "很遗憾，没有相关记录！", Toast.LENGTH_SHORT).show();
        } else {
            SimpleAdapter simpleAdapter = new SimpleAdapter(AddDanciActivity.this, resultList, R.layout.item, new String[]{"word", "interpret"
            }, new int[]{R.id.textView, R.id.textView2});
            listview.setAdapter(simpleAdapter);
        }
    }

    @Override
    protected void onStart() {
        super.onStart();
        renew();
    }
}

DBOpenHelper.java

用到的是SQLite数据库，Android自带了一种轻量级数据库，使用非常方便。

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import androidx.annotation.Nullable;

public class DBOpenHelper extends SQLiteOpenHelper {

    final String CREATE_TABLE_SQL = "create table tb_dict (_id integer primary key autoincrement,word,detail)";//定义创建表的

    public DBOpenHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, null, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLE_SQL);//创建单词的数据表
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.i("词典", "--版本更新" + oldVersion + "-->" + newVersion);
    }
}

效果图

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