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这篇文章将为大家详细讲解有关怎么让java只根据数据库表名自动生成实体类，小编觉得挺实用的，因此分享给大家做个参考，希望大家阅读完这篇文章后可以有所收获。
公司用的jpa，没有用mybatis。所以也没有用mybatis自动生成。但有些数据库表字段太多，就想着一劳永逸了，连数据库注释都搞上去
第一种
这里使用的是jdbcTemplate+Junit测试生成，方式可变。
SpringBoot版本是2.4.4,只需要加上@SpringBootTest就可以了。不用@RunWith
pom:
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> </dependency>
代码
package com.shinedata.bims.web;
import org.apache.commons.collections.MapUtils;
import org.apache.commons.lang3.StringUtils;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @ClassName TestController
* @Author yupanpan
* @Date 2021/4/12 14:24
*/
@SpringBootTest
public class TestController {
@Autowired
private JdbcTemplate jdbcTemplate;
@Test
public void database(){
createEntity("1ceping", "t_evaluation_template_info_copy","com.shinedata.bims.entity",false);
}
/**
*
* @param dataBaseName 数据库名
* @param tableName 表名
* @param packageName 包名
* @param isAddEntitySuffix 类名是否添加Entity后缀 true-添加 false-不添加
*/
public void createEntity(String dataBaseName,String tableName,String packageName,boolean isAddEntitySuffix){
String className=tableName;
if(tableName.substring(0,2).equals("t_")){
StringBuilder stringBuilder = new StringBuilder(tableName);
stringBuilder.replace(0, 2, "");
String initialsUpperCase = stringBuilder.substring(0, 1).toUpperCase();
className=initialsUpperCase+stringBuilder.substring(1);
}
className=removeUnderline(className)+(isAddEntitySuffix?"Entity":"");
StringBuffer classBuffer=new StringBuffer();
classBuffer.append("import java.util.Date;\r\n");
classBuffer.append("import java.time.LocalDateTime;\r\n");
classBuffer.append("import com.alibaba.fastjson.JSONObject;\r\n");
classBuffer.append("import java.lang.*;\r\n");
classBuffer.append("import java.math.*;\r\n");
classBuffer.append("import java.sql.*;\r\n");
classBuffer.append("import lombok.Data;\r\n\r\n\r\n");
classBuffer.append("@Data\r\n");
classBuffer.append("public class " + className + " {\r\n\r\n");
List<Map> filedMaps = getFiledMaps(dataBaseName, tableName);
processAllAttrs(classBuffer,filedMaps);
classBuffer.append("}\r\n");
markerBean(className,classBuffer.toString(),packageName);
}
/**
* 创建实体类文件
* @param className 类名(不包含.java文件名后缀) 根据表名首字母大写并去掉开头t_和所有下划线-驼峰命名
* @param content 添加的内容(字段注释等)
* @param packageName 包名(com.xxx.xxx.xxx)
*/
public void markerBean(String className, String content, String packageName) {
String folder = System.getProperty("user.dir") + "/src/main/java/" + packageName.replace(".","/") + "/";
File file = new File(folder);
if (!file.exists()) {
file.mkdirs();
}
String fileName = folder + className + ".java";
try {
File newjava = new File(fileName);
FileWriter fw = new FileWriter(newjava);
fw.write("package\t" + packageName + ";\r\n");
fw.write(content);
fw.flush();
fw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 解析输出属性
*
* @return
*/
private void processAllAttrs(StringBuffer sb,List<Map> filedMaps) {
for (int i = 0; i < filedMaps.size(); i++) {
Map map = filedMaps.get(i);
String fieldType = MapUtils.getString(map, "fieldType");
String fieldName = MapUtils.getString(map, "fieldName");
String fieldComment = MapUtils.getString(map, "fieldComment");
if(StringUtils.isNotBlank(fieldComment)){
sb.append("\t/**\r\n").append("\t* ").append(fieldComment).append("\n").append("\t*/\r\n");
}
sb.append("\tprivate " + fieldType + " " + fieldName + ";\r\n\r\n");
}
}
/**
* 获取表字段信息(列名、类型、注释等)
* @param dataBaseName
* @param tableName
* @return
*/
private List<Map> getFiledMaps(String dataBaseName,String tableName) {
String sql="SELECT * FROM information_schema.`COLUMNS` WHERE TABLE_SCHEMA ='"+dataBaseName+"' AND TABLE_NAME = '"+tableName+"'";
List<Map> tableFieldList = jdbcTemplate.query(sql, new RowMapper<Map>() {
@Override
public Map<String,String> mapRow(ResultSet resultSet, int rowNum) throws SQLException {
Map<String,String> fieldMap = new HashMap();
String column_name = resultSet.getString("COLUMN_NAME");
setFieldName(column_name.toLowerCase(),fieldMap);
String data_type = resultSet.getString("DATA_TYPE");
setFieldType(data_type.toUpperCase(),fieldMap);
fieldMap.put("fieldComment",resultSet.getString("COLUMN_COMMENT"));
return fieldMap;
}
});
return tableFieldList;
}
private void setFieldName(String columnName, Map fieldMap) {
fieldMap.put("fieldName",removeUnderline(columnName));
}
/**
* 去下划线
* @param string
* @return
*/
public String removeUnderline(String string){
StringBuilder columnNameBuilder=new StringBuilder(string);
if(!string.contains("_")){
return string;
}else {
int i = columnNameBuilder.indexOf("_");
columnNameBuilder.replace(i,i+1, "").replace(i,i+1,columnNameBuilder.substring(i,i+1).toUpperCase());
return removeUnderline(columnNameBuilder.toString());
}
}
private void setFieldType(String columnType,Map fieldMap){
String fieldType="String";
if(columnType.equals("INT")||columnType.equals("INTEGER")){
fieldType="Integer";
}else if(columnType.equals("BIGINT")){
fieldType="Long";
}else if(columnType.equals("DATETIME")){
fieldType="Date";
}else if(columnType.equals("TEXT")||columnType.equals("VARCHAR")||columnType.equals("TINYTEXT")||columnType.equals("LONGTEXT")){
fieldType="String";
}else if(columnType.equals("DOUBLE")){
fieldType="Double";
}else if(columnType.equals("BIT")){
fieldType="Boolean";
}else if(columnType.equals("FLOAT")){
fieldType="Float";
}else if(columnType.equals("DECIMAL")){
fieldType="BigDecimal";
}else if(columnType.equals("DATE")){
fieldType="Date";
}else if(columnType.equals("TIMESTAMP")){
fieldType="LocalDateTime";
}else if(columnType.equals("CHAR")){
fieldType="Char";
}else if(columnType.equals("JSON")){//mysql5.7版本才开始有的
fieldType="JSONObject";
}
fieldMap.put("fieldType",fieldType);
}
}生成的类
用的lombok，就懒得去搞getset了
第二种
搞的是直接main方法运行下就生成，大同小异。不用Junit，方便一些，就是个工具。和第一种结果一样的
package com.shinedata.bims.web;
import org.apache.commons.collections.MapUtils;
import org.apache.commons.lang3.StringUtils;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.*;
import java.util.*;
/**
* @ClassName TableToEntityUtils
* @Author yupanpan
* @Date 2021/6/8 17:25
*/
public class TableToEntityUtils {
static final String USER = "root";
static final String PASS = "xxxxxxxxxxx";
// static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
// MySQL 8.0 以下版本 - JDBC 驱动名及数据库 URL
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://xxxxxxxxxxxxxxxxxxxxxxx:3306/1ceping?useUnicode=true&characterEncoding=UTF8&zeroDateTimeBehavior=convertToNull&autoReconnect=true&allowMultiQueries=true&rewriteBatchedStatements=true";
public static void main(String[] args) throws Exception {
createEntity("1ceping", "t_evaluation_template_info_copy","com.shinedata.bims.entity",false);
}
/**
*
* @param dataBaseName 数据库名
* @param tableName 表名
* @param packageName 包名
* @param isAddEntitySuffix 类名是否添加Entity后缀 true-添加 false-不添加
*/
public static void createEntity(String dataBaseName, String tableName, String packageName, boolean isAddEntitySuffix) throws Exception{
String className=tableName;
if(tableName.substring(0,2).equals("t_")){
StringBuilder stringBuilder = new StringBuilder(tableName);
stringBuilder.replace(0, 2, "");
String initialsUpperCase = stringBuilder.substring(0, 1).toUpperCase();
className=initialsUpperCase+stringBuilder.substring(1);
}
className=removeUnderline(className)+(isAddEntitySuffix?"Entity":"");
StringBuffer classBuffer=new StringBuffer();
classBuffer.append("import java.util.Date;\r\n");
classBuffer.append("import java.time.LocalDateTime;\r\n");
classBuffer.append("import com.alibaba.fastjson.JSONObject;\r\n");
classBuffer.append("import java.lang.*;\r\n");
classBuffer.append("import java.math.*;\r\n");
classBuffer.append("import java.sql.*;\r\n");
classBuffer.append("import lombok.Data;\r\n\r\n\r\n");
classBuffer.append("@Data\r\n");
classBuffer.append("public class " + className + " {\r\n\r\n");
List<Map> filedMaps = getFiledMaps(dataBaseName, tableName);
processAllAttrs(classBuffer,filedMaps);
classBuffer.append("}\r\n");
markerBean(className,classBuffer.toString(),packageName);
}
/**
* 创建实体类文件
* @param className 类名(不包含.java文件名后缀) 根据表名首字母大写并去掉开头t_和所有下划线-驼峰命名
* @param content 添加的内容(字段注释等)
* @param packageName 包名(com.xxx.xxx.xxx)
*/
public static void markerBean(String className, String content, String packageName) throws Exception {
// 这里不使用System.getProperty("user.dir")了。user.dir是根据运行时环境来的
File f2 = new File(TableToEntityUtils.class.getResource("/").getPath());
String homePath=f2.getCanonicalPath().replace("\\target\\classes", "");
String folder = homePath + "/src/main/java/" + packageName.replace(".","/") + "/";
File file = new File(folder);
if (!file.exists()) {
file.mkdirs();
}
String fileName = folder + className + ".java";
try {
File newjava = new File(fileName);
FileWriter fw = new FileWriter(newjava);
fw.write("package\t" + packageName + ";\r\n");
fw.write(content);
fw.flush();
fw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 去下划线
* @param string
* @return
*/
public static String removeUnderline(String string){
StringBuilder columnNameBuilder=new StringBuilder(string);
if(!string.contains("_")){
return string;
}else {
int i = columnNameBuilder.indexOf("_");
columnNameBuilder.replace(i,i+1, "").replace(i,i+1,columnNameBuilder.substring(i,i+1).toUpperCase());
return removeUnderline(columnNameBuilder.toString());
}
}
/**
* 获取表字段信息(列名、类型、注释等)
* @param dataBaseName
* @param tableName
* @return
*/
private static List<Map> getFiledMaps(String dataBaseName, String tableName) {
Connection conn = null;
Statement stmt = null;
List<Map> tableFieldList=new ArrayList<>();
try{
// 注册 JDBC 驱动
Class.forName(JDBC_DRIVER);
conn = DriverManager.getConnection(DB_URL,USER,PASS);
// 执行查询
stmt = conn.createStatement();
String sql= "SELECT * FROM information_schema.`COLUMNS` WHERE TABLE_SCHEMA ='"+dataBaseName+"' AND TABLE_NAME= '"+tableName+"'";
ResultSet rs = stmt.executeQuery(sql);
while (rs.next()) {
Map<String,String> fieldMap = new HashMap();
String column_name = rs.getString("COLUMN_NAME");
setFieldName(column_name.toLowerCase(),fieldMap);
String data_type = rs.getString("DATA_TYPE");
setFieldType(data_type.toUpperCase(),fieldMap);
fieldMap.put("fieldComment",rs.getString("COLUMN_COMMENT"));
tableFieldList.add(fieldMap);
}
rs.close();
stmt.close();
conn.close();
}catch(SQLException se){
// 处理 JDBC 错误
se.printStackTrace();
}catch(Exception e){
// 处理 Class.forName 错误
e.printStackTrace();
}finally{
// 关闭资源
try{
if(stmt!=null){
stmt.close();
}
}catch(SQLException se2){
}// 什么都不做
try{
if(conn!=null) conn.close();
}catch(SQLException se){
se.printStackTrace();
}
}
return tableFieldList;
}
/**
* 解析输出属性
*
* @return
*/
private static void processAllAttrs(StringBuffer sb, List<Map> filedMaps) {
for (int i = 0; i < filedMaps.size(); i++) {
Map map = filedMaps.get(i);
String fieldType = MapUtils.getString(map, "fieldType");
String fieldName = MapUtils.getString(map, "fieldName");
String fieldComment = MapUtils.getString(map, "fieldComment");
if(StringUtils.isNotBlank(fieldComment)){
sb.append("\t/**\r\n").append("\t* ").append(fieldComment).append("\n").append("\t*/\r\n");
}
sb.append("\tprivate " + fieldType + " " + fieldName + ";\r\n\r\n");
}
}
private static void setFieldName(String columnName, Map fieldMap) {
fieldMap.put("fieldName",removeUnderline(columnName));
}
private static void setFieldType(String columnType, Map fieldMap){
String fieldType="String";
if(columnType.equals("INT")||columnType.equals("INTEGER")){
fieldType="Integer";
}else if(columnType.equals("BIGINT")){
fieldType="Long";
}else if(columnType.equals("DATETIME")){
fieldType="Date";
}else if(columnType.equals("TEXT")||columnType.equals("VARCHAR")||columnType.equals("TINYTEXT")||columnType.equals("LONGTEXT")){
fieldType="String";
}else if(columnType.equals("DOUBLE")){
fieldType="Double";
}else if(columnType.equals("BIT")){
fieldType="Boolean";
}else if(columnType.equals("FLOAT")){
fieldType="Float";
}else if(columnType.equals("DECIMAL")){
fieldType="BigDecimal";
}else if(columnType.equals("DATE")){
fieldType="Date";
}else if(columnType.equals("TIMESTAMP")){
fieldType="LocalDateTime";
}else if(columnType.equals("CHAR")){
fieldType="Char";
}else if(columnType.equals("JSON")){//mysql5.7版本才开始有的
fieldType="JSONObject";
}
fieldMap.put("fieldType",fieldType);
}
}关于“怎么让java只根据数据库表名自动生成实体类”这篇文章就分享到这里了，希望以上内容可以对大家有一定的帮助，使各位可以学到更多知识，如果觉得文章不错，请把它分享出去让更多的人看到。
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