注意：

StudentDao为新生成的也就是java工程类里面新添加字段时生成的类，而StudentDao1则是刚开始生成的类。
仅仅只有上面一个类还是不行的我们还需要一个类对数据库已有的内容进行操作，其实很简单，就是新建一个临时表，将原来已有的数据写入到临时表中，然后再将临时表中的数据写入到新表中。下面的代码是我在网上找的，效果还可以

public class MigrationHelper {    /**     * 调用升级方法     * @param db     * @param daoClasses 一系列dao.class     */    public static void migrate(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {        //1 新建临时表        generateTempTables(db, daoClasses);        //2 创建新表        createAllTables(db, false, daoClasses);        //3 临时表数据写入新表，删除临时表        restoreData(db, daoClasses);    }    /**     * 生成临时表，存储旧的表数据     * @param db     * @param daoClasses     */    private static void generateTempTables(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {        //方法2        for (int i=0;inew DaoConfig(db,daoClasses[i]);            String tableName = daoConfig.tablename;            if (!checkTable(db,tableName))                continue;            String tempTableName = daoConfig.tablename.concat("_TEMP");            StringBuilder insertTableStringBuilder = new StringBuilder();            insertTableStringBuilder.append("alter table ")                    .append(tableName)                    .append(" rename to ")                    .append(tempTableName)                    .append(";");            db.execSQL(insertTableStringBuilder.toString());        }    }    /**     * 检测table是否存在     * @param db     * @param tableName     */    private static Boolean checkTable(SQLiteDatabase db,String  tableName){        StringBuilder query = new StringBuilder();        query.append("SELECT count(*) FROM sqlite_master WHERE type='table' AND name='").append(tableName).append("'");        Cursor c = db.rawQuery(query.toString(), null);        if (c.moveToNext()){            int count = c.getInt(0);            if(count>0){               return true;            }            return false;        }        return false;    }    /**     * 删除所有旧表     * @param db     * @param ifExists     * @param daoClasses     */    private static void dropAllTables(SQLiteDatabase db, boolean ifExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {        reflectMethod(db, "dropTable", ifExists, daoClasses);    }    /**     * 创建新的表结构     * @param db     * @param ifNotExists     * @param daoClasses     */    private static void createAllTables(SQLiteDatabase db, boolean ifNotExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {        reflectMethod(db, "createTable", ifNotExists, daoClasses);    }    /**     * 创建根删除都在StudentDao声明了，可以直接拿过来用     * dao class already define the sql exec method, so just invoke it     */    private static void reflectMethod(SQLiteDatabase db, String methodName, boolean isExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {        if (daoClasses.length < 1) {            return;        }        try {            for (Class cls : daoClasses) {                //根据方法名，找到声明的方法                Method method = cls.getDeclaredMethod(methodName, SQLiteDatabase.class, boolean.class);                method.invoke(null, db, isExists);            }        } catch (NoSuchMethodException e) {            e.printStackTrace();        } catch (InvocationTargetException e) {            e.printStackTrace();        } catch (IllegalAccessException e) {            e.printStackTrace();        }    }    /**     * 临时表的数据写入新表     * @param db     * @param daoClasses     */    private static void restoreData(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {        for (int i = 0; i < daoClasses.length; i++) {            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);            String tableName = daoConfig.tablename;            String tempTableName = daoConfig.tablename.concat("_TEMP");            if (!checkTable(db,tempTableName))                continue;            // get all columns from tempTable, take careful to use the columns list            List columns = getColumns(db, tempTableName);            //新表，临时表都包含的字段            ArrayList properties = new ArrayList<>(columns.size());            for (int j = 0; j < daoConfig.properties.length; j++) {                String columnName = daoConfig.properties[j].columnName;                if (columns.contains(columnName)) {                    properties.add(columnName);                }            }            if (properties.size() > 0) {                final String columnSQL = TextUtils.join(",", properties);                StringBuilder insertTableStringBuilder = new StringBuilder();                insertTableStringBuilder.append("INSERT INTO ").append(tableName).append(" (");                insertTableStringBuilder.append(columnSQL);                insertTableStringBuilder.append(") SELECT ");                insertTableStringBuilder.append(columnSQL);                insertTableStringBuilder.append(" FROM ").append(tempTableName).append(";");                db.execSQL(insertTableStringBuilder.toString());            }            StringBuilder dropTableStringBuilder = new StringBuilder();            dropTableStringBuilder.append("DROP TABLE ").append(tempTableName);            db.execSQL(dropTableStringBuilder.toString());        }    }    private static List getColumns(SQLiteDatabase db, String tableName) {        List columns = null;        Cursor cursor = null;        try {            cursor = db.rawQuery("SELECT * FROM " + tableName + " limit 0", null);            if (null != cursor && cursor.getColumnCount() > 0) {                columns = Arrays.asList(cursor.getColumnNames());            }        } catch (Exception e) {            e.printStackTrace();        } finally {            if (cursor != null)                cursor.close();            if (null == columns)                columns = new ArrayList<>();        }        return columns;    }}

MainActivity类

package com.liuyongxiang.robert.greendao;import android.app.Activity;import android.os.Bundle;import android.widget.Button;import com.liuyongxiang.robert.greendao.daomanager.CommonUtils;import com.liuyongxiang.robert.greendao.lyxdao.Student;import java.util.ArrayList;import java.util.List;import butterknife.BindView;import butterknife.ButterKnife;import butterknife.OnClick;public class MainActivity extends Activity {    @BindView(R.id.btn_add)    Button btnAdd;    @BindView(R.id.btn_delete)    Button btnDelete;    @BindView(R.id.btn_modify)    Button btnModify;    @BindView(R.id.btn_query)    Button btnQuery;    @BindView(R.id.btn_multi_add)    Button btnMultiAdd;    @BindView(R.id.btn_multi_query)    Button btnMultiQuery;    @BindView(R.id.btn_add_param)    Button btnAddParam;    private CommonUtils commonUtils;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        ButterKnife.bind(this);        commonUtils = new CommonUtils(this);    }    @OnClick(R.id.btn_add)    void addData() {        Student student = new Student();        student.setId(1001L);        student.setAddress("北京市昌平区" + 1 + "号院");        student.setName("张三");        student.setAge(22);        commonUtils.insertStudent(student);    }    @OnClick(R.id.btn_multi_add)    void addMultiData() {        List sList = new ArrayList<>();        for (int i = 1; i < 11; i++) {            Student student = new Student();            student.setAddress("北京市昌平区" + i + "号院");            student.setName("张三" + i);            student.setAge(22 + i);            sList.add(student);        }        commonUtils.insertMultiStudent(sList);    }    @OnClick(R.id.btn_delete)    void deleteData() {        Student student = new Student();        student.setId(1003L);        commonUtils.deleteStudent(student);    }    @OnClick(R.id.btn_modify)    void modifyData() {        Student student = new Student();        student.setId(1002L);        student.setName("王五");        student.setAddress("北京市朝阳区");        student.setAge(26);        commonUtils.modifyStudent(student);    }    @OnClick(R.id.btn_query)    void queryData() {        commonUtils.queryStudent(1001L);    }    @OnClick(R.id.btn_multi_query)    void queryMultiData() {        commonUtils.queryAllStudent();    }    @OnClick(R.id.btn_add_param)    void addParamData(){        commonUtils.onUpgrade();        Student student = new Student();        student.setAddress("北京市昌平区");        student.setName("赵六");        student.setAge(24);        student.setSex("男");        commonUtils.insertStudent(student);    }}

数据库升级之前

数据库升级之后

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