JAVA操作mysql(如何更加面向对象的操作数据库)

既然谈到面向对象，所以，先把连接信息给搞个对象出来：

public class DBInfo {
    
    private String driver;
    
    private String host;
    
    private String port;
    
    private String user;
    
    private String pwd;
    
    private String dataBase;
    
    public DBInfo(){        
        this.driver = "com.mysql.jdbc.Driver";
        this.host = "";
        this.port = "";
        this.user = "";
        this.pwd = "";
        this.dataBase = "";
    }

    public String getDriver() {
        return driver;
    }

    public void setDriver(String driver) {
        this.driver = driver;
    }

    public String getHost() {
        return host;
    }

    public void setHost(String host) {
        this.host = host;
    }

    public String getDataBase() {
        return dataBase;
    }

    public void setDataBase(String dataBase) {
        this.dataBase = dataBase;
    }

    public String getPort() {
        return port;
    }

    public void setPort(String port) {
        this.port = port;
    }

    public String getUser() {
        return user;
    }

    public void setUser(String user) {
        this.user = user;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }    
    
}

既然是操作数据库，我们就把数据库的字段给对象化一下，也就是持久化：在定义变量时，我们搞个约定，比如，数据库字段名为:test_login_name,则定义变量时为：testLoginName.

public class UserInfo {
    
    private int id;
    
    private String testName;
    
    private String testAge;
    
    private String testHeight;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTestName() {
        return testName;
    }

    public void setTestName(String testName) {
        this.testName = testName;
    }

    public String getTestAge() {
        return testAge;
    }

    public void setTestAge(String testAge) {
        this.testAge = testAge;
    }

    public String getTestHeight() {
        return testHeight;
    }

    public void setTestHeight(String testHeight) {
        this.testHeight = testHeight;
    }    
    
}

好，现在有了javabean,有了数据库连接的对象了，再加一个枚举来保存数据库与bean之间的映射关系：

public enum TableBean {
    
    USER_INFO("com.test.bean.UserInfo");
         
    private String value;
     
    private TableBean(String value){
        this.value = value;
    }
     
    public String getValue(){
        return value;
    }
    @Override
    public String toString() {
            return value;              
    }
     
    public static void main(String[] args){
       System.out.println(TableBean.USER_INFO);
    }
    
}

再加一个保存ResultSetMetaData信息的类:

public class MetaData {
    
    public static Map<String, ResultSetMetaData> metaData = new HashMap<String, ResultSetMetaData>();
    
}

余下就是操作数据库了：

public class ConnectToMySQL {

    private DBInfo dbInfo;

    private Connection conn = null;

    private Statement stmt = null;
    
    public ConnectToMySQL(){
        dbInfo = new DBInfo();
    }    

    public DBInfo getDbInfo() {
        return dbInfo;
    }

    public void setDbInfo(DBInfo dbInfo) {
        this.dbInfo = dbInfo;
    }

    public void connect() {
        this.close();    
        this.connectMySQL();
    }

    public synchronized void close() {
        try {
            if (stmt != null) {
                stmt.close();
                stmt = null;
            }
            if (conn != null) {
                conn.close();
                conn = null;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private synchronized void connectMySQL() {
        try {
            Class.forName(dbInfo.getDriver()).newInstance();
            conn = (Connection) DriverManager.getConnection("jdbc:mysql://"
                    + dbInfo.getHost() + "/" + dbInfo.getDataBase() +"?useUnicode=true&characterEncoding=utf-8", dbInfo.getUser(),dbInfo.getPwd());
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }

    private void statement() {
        if (conn == null) {
            this.connectMySQL();
        }
        try {
            stmt = (Statement) conn.createStatement();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private ResultSet resultSet(String sql) {
        ResultSet rs = null;
        if (stmt == null) {
            this.statement();
        }
        try {
            rs = stmt.executeQuery(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
    
    private void executeUpdate(String sql){
        if (stmt == null) {
            this.statement();
        }
        try {
            stmt.executeUpdate(sql);
        } catch (SQLException e) {
            System.out.println(sql);
            e.printStackTrace();
        }
    }

    public List<Object> query(String tableInfo, String sql) {
        List<Object> list = new ArrayList<Object>();        
        ResultSet rs = this.resultSet(sql);        
        try {
            ResultSetMetaData md = rs.getMetaData();
            int cc = md.getColumnCount();
            while (rs.next()) {    
                Object object = this.getBeanInfo(tableInfo);
                for (int i = 1; i <= cc; i++) {
                    String cn = md.getColumnName(i);                    
                    this.reflectSetInfo(object, this.changeColumnToBean(cn,"set"), rs.getObject(cn));
                }    
                list.add(object);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;
    }
    
    public void insert(String table, Object object){        
        String sql = "";
        try {
            this.getMetaData(table);
            ResultSetMetaData md = MetaData.metaData.get(table);            
            int cc = md.getColumnCount();
            String insertColumn = "";
            String insertValue = "";
            for (int i = 2; i <= cc; i++) {
                String cn = md.getColumnName(i);                
                Object gValue = this.reflectGetInfo(object, this.changeColumnToBean(cn,"get"));
                if(gValue.getClass().getSimpleName().equals("String")){
                    gValue = """+gValue+""";
                }
                if("".equals(insertColumn)){
                    insertColumn += cn;
                    insertValue += gValue;                    
                }else{
                    insertColumn += ","+cn;
                    insertValue += ","+gValue;
                }                
            }
            sql = "insert into "+table+" ("+insertColumn+") values ("+insertValue+")";            
            this.executeUpdate(sql);
        } catch (SQLException e) {            
            e.printStackTrace();
        }        
    } 
    
    private void getMetaData(String table){        
        if(!MetaData.metaData.containsKey(table)){
            ResultSet rs = this.resultSet("select * from "+table+" limit 0,1");
            try {                
                MetaData.metaData.put(table, rs.getMetaData());
            } catch (SQLException e) {                
                e.printStackTrace();
            }
        }
    }
    
    private Object getBeanInfo(String tableInfo){
        Object object = null;
        try {
            object = Class.forName(tableInfo).newInstance();
        } catch (InstantiationException e) {            
            e.printStackTrace();
        } catch (IllegalAccessException e) {            
            e.printStackTrace();
        } catch (ClassNotFoundException e) {            
            e.printStackTrace();
        }
        return object;
    }
    
    private void reflectSetInfo(Object object, String methodName, Object parameter){
        try {    
            Class<? extends Object> ptype = parameter.getClass();            
            if(parameter.getClass().getSimpleName().equals("Integer")){
                ptype = int.class;
            }
            Method method = object.getClass().getMethod(methodName, ptype);            
            method.invoke(object, parameter);                                
        } catch (SecurityException e) {            
            e.printStackTrace();
        } catch (NoSuchMethodException e) {            
            e.printStackTrace();
        } catch (IllegalArgumentException e) {            
            e.printStackTrace();
        } catch (IllegalAccessException e) {            
            e.printStackTrace();
        } catch (InvocationTargetException e) {            
            e.printStackTrace();
        }
    }
    
    private Object reflectGetInfo(Object object, String methodName){
        Object value = null;        
        try {
            Method method = object.getClass().getMethod(methodName);            
            Object returnValue = method.invoke(object);
            if(returnValue!=null){
                value = returnValue.toString();
            }else{
                value = "";
            }
        } catch (SecurityException e) {            
            e.printStackTrace();
        } catch (NoSuchMethodException e) {            
            e.printStackTrace();
        } catch (IllegalArgumentException e) {            
            e.printStackTrace();
        } catch (IllegalAccessException e) {            
            e.printStackTrace();
        } catch (InvocationTargetException e) {            
            e.printStackTrace();
        }
        return value;    
    }
    
    private String columnToBean(String column){        
        if(column.contains("_")){
            int index = column.indexOf("_");
            String beanName = column.substring(0, index)
                             +column.substring(index+1, index+2).toUpperCase()
                             +column.substring(index+2, column.length());            
            return beanName;
        }        
        return column;
    }
    
    private String changeColumnToBean(String column, String ext){
        String[] col = column.split("_");
        for (int i = 0; i < col.length; i++) {
            column = this.columnToBean(column);
        }
        column =column.replaceFirst(column.substring(0, 1), column.substring(0, 1).toUpperCase());
        column = ext+column;
        return column;
    }

    public static void main(String[] args) throws SQLException {
        ConnectToMySQL c = new ConnectToMySQL();
        c.connect();
        List<Object> list = c.query(TableBean.APK_INFO.toString(), "select * from user_info");
        
        c.insert("user_info", (UserInfo)list.get(0));
        c.close();
    }
}

仔细看看吧，query出来就是对象的集合，insert时，就是表名与对象就行了，至于update与delete，大家自已扩展吧！

如果把这个摸清楚，spring操作mysql数据库的原理，你也就差不多了！