DBUnit使用介绍

一、DbUnit设计理念
熟悉单元测试的开发人员都知道，在对数据库进行单元测试时候，通常采用的方案有运用模拟对象(mock objects)和stubs两种。通过隔离关联的数据库访问类，比如JDBC的相关操作类，来达到对数据库操作的模拟测试。然而某些特殊的系统，比如利 用了EJB的CMP(container-managed persistence)的系统，数据库的访问对象是在最底层而且很隐蔽的，那么这两种解决方案对这些系统就显得力不从心了。
DBUnit的设计理念就是在测试之前，备份数据库，然后给对象数据库植入我们需要的准备数据，最后，在测试完毕后，读入备份数据库，回溯到测试前的状态；而且又因为DBUnit是对JUnit的一种扩展，开发人员可以通过创建测试用例代码，在这些测试用例的生命周期内来对数据库的操作结果进行比较。

二、DbUnit测试基本概念和流程
基于DbUnit 的测试的主要接口是IDataSet。IDataSet代表一个或多个表的数据。
可以将数据库模式的全部内容表示为单个IDataSet 实例。这些表本身由Itable 实例来表示。
IDataSet 的实现有很多，每一个都对应一个不同的数据源或加载机制。最常用的几种 IDataSet实现为:

FlatXmlDataSet：数据的简单平面文件 XML 表示 
QueryDataSet：用 SQL 查询获得的数据 
DatabaseDataSet：数据库表本身内容的一种表示 
XlsDataSet ：数据的excel表示

DBUnit支持的数据库包括，db2,h2,hsqldb,mckoi,mssql,mysql,netezza,oralce,postgresql.

三、DBUnit测试流程：

一般而言，使用DbUnit进行单元测试的流程如下：
1 根据业务，做好测试用的准备数据和预想结果数据，通常准备成xml格式文件。
2 在setUp()方法里边备份数据库中的关联表。
3 在setUp()方法里边读入准备数据。
4 对测试类的对应测试方法进行实装:执行对象方法，把数据库的实际执行结果和预想结果进行比较。
5 在tearDown()方法里边,把数据库还原到测试前状态。

 四、实例开发：

1、新建一个pom工程，加入相关依赖:

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.dbunit</groupId>
        <artifactId>dbunit</artifactId>
        <version>2.5.3</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-nop</artifactId>
        <version>1.7.24</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.38</version>
    </dependency>

2、新建工程相关目录

BaseDao.java文件：

public class BaseDao {
    private static Connection CONNECTION_INSTANCE = null;
    
    protected Connection getConnection() throws Exception{
        if(null==CONNECTION_INSTANCE){
            Class.forName("com.mysql.jdbc.Driver");
            CONNECTION_INSTANCE=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test","root","root");
        }
        return CONNECTION_INSTANCE;
    }
    
    protected void closeConnection() throws Exception{
        if(null!=CONNECTION_INSTANCE){
            if(!CONNECTION_INSTANCE.isClosed()){
                CONNECTION_INSTANCE.close();
            }
            CONNECTION_INSTANCE=null;
        }
    }
}

DBUnitUtils.java文件

public class DBUnitUtils {
    
    //产生数据集
    public static void generateDatasetDtd(String[] tables) throws Exception{
        QueryDataSet dataSet=new QueryDataSet(DButils.getDataBaseConnection());
        for(String _table:tables){
            dataSet.addTable(_table);
        }
        FlatDtdDataSet.write(dataSet, new FileOutputStream(new File("resource/tmp.dtd")));
        //FlatXmlDataSet.write(dataSet,new FileOutputStream(new File("resource/dbunit1.xml")));  
    }
    
    //备份表数据
    public static void backupDatabase(String[] tables,File backupFile) throws Exception{
        QueryDataSet dataSet=new QueryDataSet(DButils.getDataBaseConnection());
        for(String _table:tables){
            dataSet.addTable(_table);
        }
        FlatXmlDataSet.write(dataSet, new FileOutputStream(backupFile));
    }
    
    //清空表数据，并导入测试数据
    public static void importTables(File dataFile) throws Exception{
        IDataSet dataSet=new FlatXmlDataSetBuilder().build(dataFile);
        DatabaseOperation.CLEAN_INSERT.execute(DButils.getDataBaseConnection(), dataSet);
    }
    
    //清空表数据，恢复备份数据
    public static void resumeDatabase(File backupFile) throws Exception{
        IDataSet dataSet=new FlatXmlDataSetBuilder().build(backupFile);
        DatabaseOperation.CLEAN_INSERT.execute(DButils.getDataBaseConnection(), dataSet);        
    }
}

DButils.java文件

public class DButils {
    private static IDatabaseConnection conn;
    
    //通过dbUnit创建数据库连接
    public static IDatabaseConnection getDataBaseConnection() throws ClassNotFoundException, SQLException, DatabaseUnitException{
        if(conn==null){
            Class.forName("com.mysql.jdbc.Driver");
            Connection dbConn=DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root");
            conn =new MySqlConnection(dbConn,"test");
            return conn;
        }
        return conn;
    }
    
    //关闭数据库连接
    public static void closeConnection(){
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        conn=null;
    }
    
}

User.java文件

public class User {    
    private long id;
    private String username;
    private String password;
    private String name;
    
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }   
}

UserService.java文件

public interface UserService {
    
    public long create(User user) throws Exception;
    
    public void update(User user) throws Exception;

    public User get(Long id) throws Exception;

    public void delete(Long id) throws Exception;

    public List<User> list() throws Exception;
}

UserServiceImpl.java文件

public class UserServiceImpl extends BaseDao implements UserService{

    //新增用户返回主键
    public long create(User user) throws Exception {
        Long id=null;
        PreparedStatement stm=getConnection().prepareStatement("insert into user(username, password, name) values(?, ?, ?)", Statement.RETURN_GENERATED_KEYS);
        stm.setString(1, user.getName());
        stm.setString(2, user.getPassword());
        stm.setString(3, user.getName());
        stm.executeUpdate();
        ResultSet rs=stm.getGeneratedKeys();
        if(rs.first()){
            id=rs.getLong(1);
        }
        return id;
    }

    //更新用户
    public void update(User user) throws Exception {
        PreparedStatement stm = getConnection().prepareStatement("update user set password = ?, name = ? where username = ?", Statement.RETURN_GENERATED_KEYS);
        stm.setString(1, user.getPassword());
        stm.setString(2, user.getName());
        stm.setString(3, user.getUsername());
        stm.executeUpdate();
        closeConnection();
    }

    //获取用户
    public User get(Long id) throws Exception {
        User user = null;
        PreparedStatement stm = getConnection().prepareStatement("select username, password, name from user where id=?");
        stm.setLong(1, id);
        ResultSet rs = stm.executeQuery();
        if (rs.first()) {
            user = new User();
            user.setUsername(rs.getString(1));
            user.setPassword(rs.getString(2));
            user.setName(rs.getString(3));
            user.setId(id);
        }
        closeConnection();
        return user;
    }

    //删除用户
    public void delete(Long id) throws Exception {
        PreparedStatement stm = getConnection().prepareStatement("delete from user where id=?");
        stm.setLong(1, id);
        stm.executeUpdate();
        closeConnection();        
    }

    //返回所有用户列表
    public List<User> list() throws Exception {
        List<User> users = new ArrayList<User>();
        PreparedStatement stm = getConnection().prepareStatement("select username, password, name, id from user");
        ResultSet rs = stm.executeQuery();
        while (rs.next()) {
            User user = new User();
            user.setUsername(rs.getString(1));
            user.setPassword(rs.getString(2));
            user.setName(rs.getString(3));
            user.setId(rs.getLong(4));
            users.add(user);
        }
        closeConnection();
        return users;
    }

}

UserServiceDBTestCase.java文件

public class UserServiceDBTestCase extends DatabaseTestCase{
    private UserService userService;
    
    @Override
    //新建一个userDao对象
    protected void setUp() throws Exception {
        super.setUp();
        userService = new UserServiceImpl();
    }

    @Override
    //清空userDao对象
    protected void tearDown() throws Exception {
        super.tearDown();
        userService = null;
    }

    @Override
    //获取数据库连接
    protected IDatabaseConnection getConnection() throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root");
        return new MySqlConnection(conn, "test");
    }

    //获取输入数据流
    @Override
    protected IDataSet getDataSet() throws Exception {
        InputStream is = getClass().getResourceAsStream("/test-data.xml");
        return new FlatXmlDataSetBuilder().build(is);
    }
    
    //测试数据的创建
    public void testCreate() throws Exception{
        User user = new User();
        user.setName("testdata");
        user.setPassword("testPassword");
        user.setUsername("testAdmin");
        Long id = userService.create(user);
        
        assertNotNull(id);
        User dbUser =userService.get(id);
        assertNotNull(dbUser);
        assertEquals("testAdmin", dbUser.getUsername());
        assertEquals("testPassword", dbUser.getPassword());
        assertEquals("testAdministrator", dbUser.getName());
    }

    public void testGet() throws Exception{
        User user = userService.get(1L);
        assertNotNull(user);
        assertEquals("admin1", user.getUsername());
        assertEquals("123", user.getPassword());
        assertEquals("Administrator1", user.getName());
        
        User nullUser = userService.get(0L);
        assertNull(nullUser);
    }
    
    public void testDelete() throws Exception{
        User user = userService.get(1L);
        assertNotNull(user);
        
        userService.delete(1L);
        User nullUser = userService.get(1L);
        assertNull(nullUser);
    }
    
    public void testList() throws Exception{
        
        List<User> users = userService.list();
        assertNotNull(users);
        assertEquals(4, users.size());
    }
    
}

UserServiceTestCase.java文件

public class UserServiceTestCase extends TestCase{
    private UserService userService;    
    private File backupFile=new File("resource/backup-data.xml");
    
    @Override
    protected void setUp() throws Exception {
        userService=new UserServiceImpl();
    }
    
    @Before
    public void setUpData() throws Exception {
        //备份原来的数据
        DBUnitUtils.backupDatabase(new String []{"user"}, backupFile);
        //导入测试数据
        DBUnitUtils.importTables(new File("resource/test-data.xml"));
    }
    
    @After
    public void tearDownData() throws Exception{
        //恢复备份数据
        DBUnitUtils.resumeDatabase(backupFile);
        //关闭数据库连接
        DButils.closeConnection();
    }
    
    public void testCreate() throws Exception{
        DBUnitUtils.importTables(new File("resource/test-data.xml"));
        User user = new User();
        DBUnitUtils.resumeDatabase(backupFile);
        DButils.closeConnection();
        user.setName("testdata");
        user.setPassword("testPassword");
        user.setUsername("testAdmin");
        Long id = userService.create(user);
        
        assertNotNull(id);
        User dbUser =userService.get(id);
        assertNotNull(dbUser);
        assertEquals("testAdmin", dbUser.getUsername());
        assertEquals("testPassword", dbUser.getPassword());
        assertEquals("testAdministrator", dbUser.getName());
    }

    public void testGet() throws Exception{
        User user = userService.get(1L);
        assertNotNull(user);
        assertEquals("admin1", user.getUsername());
        assertEquals("123", user.getPassword());
        assertEquals("Administrator1", user.getName());
        
        User nullUser = userService.get(0L);
        assertNull(nullUser);
    }
    
    public void testDelete() throws Exception{
        User user = userService.get(1L);
        assertNotNull(user);
        
        userService.delete(1L);
        User nullUser = userService.get(1L);
        assertNull(nullUser);
    }
    
    public void testList() throws Exception{        
        List<User> users = userService.list();
        assertNotNull(users);
        assertEquals(4, users.size());
    }
}

test-data.xml文件

<?xml version='1.0' encoding='UTF-8'?>
<dataset>
  <user id="1" username="test-user1" password="test-user1" name="test-user1"/>
  <user id="2" username="test-user2" password="test-user2" name="test-user2"/>
</dataset>

接下来测试结果： 

demo代码下载： dbunitDemo

总结:
使用了DBUnit后可以实现了对数据库的隔离,成功弥补了JUnit单元测试不清理数据现场的缺憾,实际上DBUnit只是简单的在单元测试前把数据库的数据进行了备份然后插入xml中配置好的数据,在测试结束后再用备份好的原数据库数据填充回数据库.但当面对复杂的表关系和大数据量的时候,每次进行测试都进行数据的备份,也是一个很大的负担,而且把全部的测试数据都编写在xml当中也是很大的工作量