开发代码生成器
- 代码生成器：可以生成代码的程序
- 代码生成器的三要素：数据+模板+合成机制
- 我们使用的模板引擎是freemarker
FreeMarker是一款模板引擎： 一种基于模板和数据，并用来生成输出文本（HTML网页、电子邮件、配置文件、源代码等）的通用工具 - 下面通过一个简单的案例来了解一下Freemarker的使用：
首先创建一个maven的工程，在pom.xml文件中添加如下依赖：
pom.xml
org.freemarker
freemarker
2.3.23
mysql
mysql-connector-java
5.1.34
下一步我们需要创建Configuration对象和Template对象，这两个对象的使用如下：
Configuration作用：环境初始化
常用的API：
| 方法名称 | 描述 |
|---|---|
| Configuration(Version incompatibleImprovements ) | 生成当前类的对象 |
| setDirectoryForTemplateLoading(File dir) | 生成当前类的对象 |
| getTemplate(String file) | 模板文件名称 |
Template作用：模板实例化，执行代码生成
常用API：
| 方法名称 | 描述 |
|---|---|
| process(Object data, Writer out) | 生成数据文件 |
代码如下：
Generator.java
public class Generator {
Configuration configuration;
//1.初始化模板配置
public void init() throws IOException {
configuration= new Configuration(Configuration.getVersion());
String templatePath = this.getClass().getClassLoader().getResource("").getPath();
//设置模板所在目录
System.out.println("templatePath:"+templatePath);
configuration.setDirectoryForTemplateLoading(new File(templatePath));
}
//2.获取模板填充数据
public void process(String tempName,Map data,String savePath) throws TemplateException, IOException {
Template template = configuration.getTemplate(tempName);
OutputStream os = new FileOutputStream(savePath);
Writer writer=new OutputStreamWriter(os);
template.process(data,writer);
}
public static void main(String[] args) throws Exception {
Generator generator = new Generator();
generator.init();
Map data=new HashMap();
data.put("name","张三11");
String savePath="F:\\generator-data\\hello.html";
generator.process("hello/hello.ftl",data,savePath);
}
}
- 了解了合成机制，那么我们的数据如何获取 - 使用JDBC获取数据库所有表信息
TableHandler.java
private static Connection connection;
private static String DBDRIVER = PropertiesUtils.get("database.properties", "driver");
private static String DBURL = PropertiesUtils.get("database.properties", "url");
private static String DBUSER = PropertiesUtils.get("database.properties", "user");
private static String DBPASS = PropertiesUtils.get("database.properties", "password");
static {
//1.获取数据库连接
try {
Class.forName(DBDRIVER);
connection = DriverManager.getConnection(DBURL,DBUSER,DBPASS);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
public void getTables() {
try {
//2.创建DatabaseMetaData
DatabaseMetaData dbmd = connection.getMetaData();
//3.执行查询
ResultSet rs = dbmd.getTables(null, null, null, new String[]{"TABLE"});
//4.遍历结果集
while (rs.next()){
String tableName = rs.getString("TABLE_NAME");
System.out.println(tableName);
}
} catch (SQLException e) {
e.printStackTrace();
}
}
public void getColumns(String tableName) {
try {
//2.获取DatabaseMetaData
DatabaseMetaData dbmd = connection.getMetaData();
//3.执行查询
ResultSet rs = dbmd.getColumns(null, "%", tableName, "%");
while(rs.next()){
//获取列名
String columnName = rs.getString("COLUMN_NAME");
//获取列类型
String columnType = rs.getString("TYPE_NAME");
//获取注释
String comment = rs.getString("REMARKS");
System.out.println("columnName:"+columnName+",columnType:"+columnType+",comment:"+comment);
}
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
TableHandler tableHandler = new TableHandler();
//tableHandler.getTables();
tableHandler.getColumns("itrip_hotel_room");
}
PropertiesUtils.java
public class PropertiesUtils {
private static Properties props;
/**
* 加载配置文件
*
* @param fileName
*/
private static void readProperties(String fileName) {
try {
props = new Properties();
InputStreamReader inputStream = new InputStreamReader(PropertiesUtils.class.getClassLoader().getResourceAsStream(fileName), "UTF-8");
props.load(inputStream);
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 根据key读取对应的value
*
* @param key
* @return
*/
public static String get(String fileName,String key) {
readProperties(fileName);
return props.getProperty(key);
}
}
database.properties
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/itripdb?useUnicode=true&characterEncoding=utf-8
user=root
password=123456
- 了解了如何获取数据，也知道了Freemaker的合成机制。下面我们可以通过模板生成实体类，SQL映射文件及映射接口。当然还有我们的service及器实现类。
database.properties ， PropertiesUtils.java同上。
（1）获取数据，修改TableHandler.java
public class TableHandler {
private static Connection connection;
private static String DBDRIVER = PropertiesUtils.get("database.properties", "driver");
private static String DBURL = PropertiesUtils.get("database.properties", "url");
private static String DBUSER = PropertiesUtils.get("database.properties", "user");
private static String DBPASS = PropertiesUtils.get("database.properties", "password");
static {
try {
Class.forName(DBDRIVER);
connection = DriverManager.getConnection(DBURL,DBUSER,DBPASS);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
public List getTables() {
List tableList = new ArrayList();
try {
DatabaseMetaData dbmd = connection.getMetaData();
ResultSet rs = dbmd.getTables(null, null, null, new String[]{"TABLE"});
while (rs.next()){
Table table = new Table();
String tableName = rs.getString("TABLE_NAME");
table.setTableName(tableName);
table.setClassName(StringUtils.captureName(StringUtils.putOffUnderline(tableName))); table.setTableNameNonUnderline(StringUtils.removeUnderlineAndSubstr(tableName)); table.setClassNameLowerFirstWord(StringUtils.lowerName(table.getClassName()));
table.setColumnList(getColumns(tableName));
tableList.add(table);
}
} catch (SQLException e) {
e.printStackTrace();
}
return tableList;
}
public List getColumns(String tableName) {
List columnList = new ArrayList();
try {
DatabaseMetaData dbmd = connection.getMetaData();
ResultSet rs = dbmd.getColumns(null, "%", tableName, "%");
while(rs.next()){
Column column =new Column();
String columnName = rs.getString("COLUMN_NAME");
String columnType = rs.getString("TYPE_NAME");
String comment = rs.getString("REMARKS");
column.setColumnName(columnName);
column.setColumnType(columnType);
column.setComments(comment);
column.setFieldName(columnName); column.setFieldNameUpperFirstWord(StringUtils.captureName(column.getFieldName()));
column.setJavaType(StringUtils.switchType(columnType));
columnList.add(column);
}
} catch (SQLException e) {
e.printStackTrace();
}
return columnList;
}
}
以上封装的过程可能需要用到对字符串的操作：
StringUtils.java
public class StringUtils {
/**
* 某位置字母大写
*
* @param name
* @param indx
* @return
*/
public static String captureName(String name, int indx) {
name = name.substring(0, indx) + name.substring(indx, indx + 1).toUpperCase() + name.substring(indx + 1);
return name;
}
/**
* 首字母大写
*
* @param name
* @return
*/
public static String captureName(String name) {
name = name.substring(0, 1).toUpperCase() + name.substring(1);
return name;
}
/***
* 首字母小写
*
* @param name
* @return
*/
public static String lowerName(String name) {
name = name.substring(0, 1).toLowerCase() + name.substring(1);
return name;
}
/***
* 去掉下划线 并用驼峰原则进行转化
*
* @return
*/
public static String putOffUnderline(String columnName) {
StringBuffer fieldNameBuffer = null;
String tempNameArray[] = columnName.split("_");
for (int i = 0; i < tempNameArray.length; i++) {
if (i == 0) {
fieldNameBuffer = new StringBuffer(tempNameArray[i]);
} else {
fieldNameBuffer.append(captureName(tempNameArray[i]));
}
}
return fieldNameBuffer.toString();
}
public static String removeUnderlineAndSubstr(String tableName){
return tableName.replaceAll("_","")
.replaceAll("itrip","");
}
/**
* 列类型转换成java类型
* @param columnType
*/
public static String switchType(String columnType){
String javaType=null;
switch (columnType){
case "BIGINT":javaType="Long";break;
case "INT":javaType="Integer";break;
case "BIT":javaType="Short";break;
case "VARCHAR":javaType="String";break;
case "TEXT":javaType="String";break;
case "DATETIME":javaType="Date";break;
case "DECIMAL":javaType="Double";break;
}
return javaType;
}
public static void main(String[] args) {
//String a = putOffUnderline("a_bccc_d");
String a=removeUnderlineAndSubstr("itrip_area_dic");
System.out.println(a);
}
}
（2）我们需要将获取到的表的数据及列的信息封装成两个实体类
Table.java
public class Table {
private String tableName;
private String className;
//类名首字母小写
private String classNameLowerFirstWord;
// 表名每个单词字母大写无下划线
private String tableNameUpperFirstWord;
private List columnList;
//表名无前缀和下划线
private String tableNameNonUnderline;
//....省略getter setter访问器
}
Column.java
public class Column {
private String columnName;
private String columnType;
private String javaType;
private String fieldName;
//属性名首字母大写
private String fieldNameUpperFirstWord;
private String comments;
//..省略getter setter访问器
}
（3）合成，修改Generator.java
public class Generator {
Configuration configuration;
//1.初始化模板配置
public void init() throws IOException {
configuration= new Configuration(Configuration.getVersion());
String templatePath = this.getClass().getClassLoader().getResource("").getPath();
//设置模板所在目录
System.out.println("templatePath:"+templatePath);
configuration.setDirectoryForTemplateLoading(new File(templatePath));
}
//2.获取模板填充数据
public void process(String tempName,Map data,String savePath) throws TemplateException, IOException {
Template template = configuration.getTemplate(tempName);
OutputStream os = new FileOutputStream(savePath);
Writer writer=new OutputStreamWriter(os);
template.process(data,writer);
}
//该方法用于生成实体类
public void executeModel() throws IOException, TemplateException {
TableHandler tableHandler = new TableHandler();
List tableList = tableHandler.getTables();
Generator generator = new Generator();
init();
for (Table table : tableList) {
Map data=new HashMap();
data.put("table",table);
File saveDir = new File("F:\\generator-data\\mymodel\\");
if(!saveDir.exists())
saveDir.mkdirs();
String savePath=saveDir+"\\"+table.getClassName()+".java";
process("itrip/model.ftl",data,savePath);
}
}
//该方法用于生成sql映射文件
public void executeMapper() throws IOException, TemplateException {
TableHandler tableHandler = new TableHandler();
List tableList = tableHandler.getTables();
Generator generator = new Generator();
init();
for (Table table : tableList) {
Map data=new HashMap();
data.put("table",table);
File saveDir = new File("F:\\generator-data\\mymapper\\");
if(!saveDir.exists())
saveDir.mkdirs();
String savePath=saveDir+"\\"+table.getClassName()+"Mapper.xml";
process("itrip/mapper.ftl",data,savePath);
}
}
//生成映射器接口
public void executeClazzMapper() throws IOException, TemplateException {
TableHandler tableHandler = new TableHandler();
List tableList = tableHandler.getTables();
Generator generator = new Generator();
init();
for (Table table : tableList) {
Map data=new HashMap();
data.put("table",table);
File saveDir = new File("F:\\generator-data\\myclazzMapper\\");
if(!saveDir.exists())
saveDir.mkdirs();
String savePath=saveDir+"\\"+table.getClassName()+"Mapper.java";
process("itrip/clazzMapper.ftl",data,savePath);
}
}
//生成service接口
public void executeService() throws IOException, TemplateException {
TableHandler tableHandler = new TableHandler();
List tableList = tableHandler.getTables();
Generator generator = new Generator();
init();
for (Table table : tableList) {
Map data=new HashMap();
data.put("table",table);
File saveDir = new File("F:\\generator-data\\myService\\");
if(!saveDir.exists())
saveDir.mkdirs();
String savePath=saveDir+"\\"+table.getClassName()+"Service.java";
process("itrip/service.ftl",data,savePath);
}
}
//生成接口实现类
public void executeServiceImpl() throws IOException, TemplateException {
TableHandler tableHandler = new TableHandler();
List tableList = tableHandler.getTables();
Generator generator = new Generator();
init();
for (Table table : tableList) {
Map data=new HashMap();
data.put("table",table);
File saveDir = new File("F:\\generator-data\\myService\\impl");
if(!saveDir.exists())
saveDir.mkdirs();
String savePath=saveDir+"\\"+table.getClassName()+"ServiceImpl.java";
process("itrip/serviceImpl.ftl",data,savePath);
}
}
public static void main(String[] args) throws Exception {
Generator generator = new Generator();
//generator.executeModel();
// generator.executeMapper();
//generator.executeClazzMapper();
generator.executeService();
}
}
（4）编辑模板：
model.ftl
package cn.itrip.beans.pojo;
import java.io.Serializable;
import java.util.Date;
public class ${table.className} implements Serializable {
<#list table.columnList as column>
private ${column.javaType} ${column.fieldName};
<#list table.columnList as column>
public void set${column.fieldNameUpperFirstWord} (${column.javaType} ${column.fieldName}){
this.${column.fieldName}=${column.fieldName};
}
public ${column.javaType} get${column.fieldNameUpperFirstWord}(){
return this.${column.fieldName};
}
}
mapper.ftl
insert into ${table.tableName}(
<#list table.columnList as column>
<#if column_has_next>
${column.columnName} ,
<#else >
${column.columnName}
)
values(
<#list table.columnList as column>
<#if column_has_next>
${r"#{"}${column.fieldName}},
<#else >
${r"#{"}${column.fieldName}}
)
update ${table.tableName}
<#list table.columnList as column>
<#if column_has_next>
${column.columnName}=${r"#{"}${column.fieldName}},
<#else >
${column.columnName}=${r"#{"}${column.fieldName}}
delete from ${table.tableName} where id = ${r"#{"}id}
clazzMapper.ftl
package cn.itrip.dao.${table.tableNameNonUnderline};
import cn.itrip.beans.pojo.${table.className};
import org.apache.ibatis.annotations.Param;
import java.util.List;
import java.util.Map;
public interface ${table.className}Mapper {
public ${table.className} get${table.className}ById(@Param(value = "id") Long id)throws Exception;
public List<${table.className}> get${table.className}ListByMap(Map param)throws Exception;
public Integer get${table.className}CountByMap(Map param)throws Exception;
public Integer insert${table.className}(${table.className} ${table.classNameLowerFirstWord})throws Exception;
public Integer update${table.className}(${table.className} ${table.classNameLowerFirstWord})throws Exception;
public Integer delete${table.className}ById(@Param(value = "id") Long id)throws Exception;
}
service.ftl
package cn.itrip.service..${table.tableNameNonUnderline};
import cn.itrip.beans.pojo.${table.className};
import java.util.List;
import java.util.Map;
import java.util.List;
import java.util.Map;
import cn.itrip.common.Page;
/**
* Created by shang-pc on 2015/11/7.
*/
public interface ${table.className}Service {
public ${table.className} get${table.className}ById(Long id)throws Exception;
public List<${table.className}> get${table.className}ListByMap(Map param)throws Exception;
public Integer get${table.className}CountByMap(Map param)throws Exception;
public Integer itriptxAdd${table.className}(${table.className} ${table.classNameLowerFirstWord})throws Exception;
public Integer itriptxModify${table.className}(${table.className} ${table.classNameLowerFirstWord})throws Exception;
public Integer itriptxDelete${table.className}ById(Long id)throws Exception;
public Page<${table.className}> query${table.className}PageByMap(Map param,Integer pageNo,Integer pageSize)throws Exception;
}
serviceImpl.ftl
package cn.itrip.service.${table.tableNameNonUnderline};
import cn.itrip.dao.${table.tableNameNonUnderline}.${table.className}Mapper;
import cn.itrip.beans.pojo.${table.className};
import cn.itrip.common.EmptyUtils;
import cn.itrip.common.Page;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Map;
import cn.itrip.common.Constants;
@Service
public class ${table.className}ServiceImpl implements ${table.className}Service {
@Resource
private ${table.className}Mapper ${table.classNameLowerFirstWord}Mapper;
public ${table.className} get${table.className}ById(Long id)throws Exception{
return ${table.classNameLowerFirstWord}Mapper.get${table.className}ById(id);
}
public List<${table.className}> get${table.className}ListByMap(Map param)throws Exception{
return ${table.classNameLowerFirstWord}Mapper.get${table.className}ListByMap(param);
}
public Integer get${table.className}CountByMap(Map param)throws Exception{
return ${table.classNameLowerFirstWord}Mapper.get${table.className}CountByMap(param);
}
public Integer itriptxAdd${table.className}(${table.className} ${table.classNameLowerFirstWord})throws Exception{
${table.classNameLowerFirstWord}.setCreationDate(new Date());
return ${table.classNameLowerFirstWord}Mapper.insert${table.className}(${table.classNameLowerFirstWord});
}
public Integer itriptxModify${table.className}(${table.className} ${table.classNameLowerFirstWord})throws Exception{
${table.classNameLowerFirstWord}.setModifyDate(new Date());
return ${table.classNameLowerFirstWord}Mapper.update${table.className}(${table.classNameLowerFirstWord});
}
public Integer itriptxDelete${table.className}ById(Long id)throws Exception{
return ${table.classNameLowerFirstWord}Mapper.delete${table.className}ById(id);
}
public Page<${table.className}> query${table.className}PageByMap(Map param,Integer pageNo,Integer pageSize)throws Exception{
Integer total = ${table.classNameLowerFirstWord}Mapper.get${table.className}CountByMap(param);
pageNo = EmptyUtils.isEmpty(pageNo) ? Constants.DEFAULT_PAGE_NO : pageNo;
pageSize = EmptyUtils.isEmpty(pageSize) ? Constants.DEFAULT_PAGE_SIZE : pageSize;
Page page = new Page(pageNo, pageSize, total);
param.put("beginPos", page.getBeginPos());
param.put("pageSize", page.getPageSize());
List<${table.className}> ${table.classNameLowerFirstWord}List = ${table.classNameLowerFirstWord}Mapper.get${table.className}ListByMap(param);
page.setRows(${table.classNameLowerFirstWord}List);
return page;
}
}
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