Java代码生成器
来公司一个月了，时间虽然不长，但是我感觉自己还是学到了不少的东西，至少在学校从没有过这样的感觉。并且我也从现在开始写博客了，希望博友能多来浏览，提出批评指正。先来看看我的第一篇博客。
事情起源于修改项目的UI（这个过程就不多说了）。我的指导人让我把项目的生成模版修改一下，适应我们的新样式，可是模版是freemarker写的，我完全都不会，没办法，只能自己去摸索了，费了九牛二虎之力终于修改好了。闲来无事，我就想这玩意好像还挺有用的，要不我也自己弄一个，于是就开始了编写我自己的代码生成器了。
好了，“废话”不多说，直接上代码。
自定义表字段结构和表结构
public class MyField {
private String field_name;
private String sql_type;
private String java_type;
private String field_comment;
private boolean is_primary;
｝public class MyTable {
//表名
private String tableName;
//普通字段集合，一个字段包括了：字段名，SQL类型，Java类型，注释，是否主键标志
private List common_fields;
//主键字段集合
private List key_fields;
//字段中是否有日期型的，如果有，那么在生成实体类时，就需要导java.util.Date包了
public boolean date_flag = false;
//字段中是否有numeric和decimal类型的，如果有，那么，在生成实体类时就需要导java.math.BigDecimal包了
public boolean math_flag = false;
//生成实体类，mapper接口等等时的基名
public String package_name_base;
｝ 工具类（里面有一部分是我最开始想纯粹用java代码来生成想要的文件，后来发现这种方法完全是硬编码，所以放弃）
public class DataBaseUtil {
private static String jdbc_url ;
private static String jdbc_driver ;
private static String jdbc_user ;
private static String jdbc_password ;
private static Integer jdbc_poolsize;
private static List connectionPool;
/**
* 静态代码块，用于读取db.properties，初始化和数据库连接相关的信息
*/
static{
Properties properties = new Properties();
InputStream input = null;
String path = "db.properties";
input = Thread.currentThread().getContextClassLoader().getResourceAsStream(path);
try {
properties.load(input);
jdbc_driver = properties.getProperty("jdbc_driver");
jdbc_url = properties.getProperty("jdbc_url");
jdbc_user = properties.getProperty("jdbc_user");
jdbc_password = properties.getProperty("jdbc_password");
jdbc_poolsize = Integer.parseInt(properties.getProperty("jdbc_poolsize"));
connectionPool = new ArrayList(jdbc_poolsize);
Class.forName(jdbc_driver);
int i;
for(i = 0 ; i < jdbc_poolsize ; i++){
Connection connection = DriverManager.getConnection(jdbc_url, jdbc_user, jdbc_password);
connectionPool.add(connection);
}
} catch (IOException e) {
System.out.println("加载属性文件失败，请检查db.properties文件是否在src下面");
System.exit(-1);
} catch (ClassNotFoundException e) {
StringBuffer buffer = new StringBuffer();
buffer.append("加载数据库驱动出错，请检查：\r\n");
buffer.append("（1）db.properties中的jdbc_driver是否写错？\r\n");
buffer.append("（2）数据库驱动JAR包是否已导入？");
System.out.println(buffer.toString());
System.exit(-1);
} catch (SQLException e) {
StringBuffer buffer = new StringBuffer();
buffer.append("Oh，My God! 数据库连接失败，请检查：\r\n");
buffer.append("（1）数据库服务是否已开启？\r\n");
buffer.append("（2）db.properties中的jdbc_url是否写错？\r\n");
buffer.append("（3）db.properties中的jdbc_user是否写错？\r\n");
buffer.append("（4）db.properties中的jdbc_password是否写错？\r\n");
System.out.println(buffer.toString());
System.exit(-1);
} finally{
try {
if(input != null)
input.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* @return 获取数据库连接，可能返回null
*/
public static Connection getConnection(){
if(connectionPool != null){
if(connectionPool.size() > 0){
return connectionPool.remove(connectionPool.size() - 1);
}else{
Connection connection = null;
try {
Class.forName(jdbc_driver);
connection = DriverManager.getConnection(jdbc_url, jdbc_user, jdbc_password);
return connection;
} catch (ClassNotFoundException e) {
e.printStackTrace();
return connection;
} catch (SQLException e) {
e.printStackTrace();
return connection;
}
}
}else
return null;
}
/**
* @return 返回某个数据库下所有的表结构
* @throws Exception
*/
public static List getAllTables(){
List tables = null;
Connection connection = getConnection();
if(connection != null){
PreparedStatement statement = null;
ResultSet connectionRS = null , queryRS = null;
tables = new ArrayList();
try {
DatabaseMetaData metaData = connection.getMetaData();
connectionRS = metaData.getTables(null, null, null, new String[]{"TABLE"});
while(connectionRS.next()){
String tableName = connectionRS.getString(3);
String querySQL = "show full columns from " + tableName;
statement = connection.prepareStatement(querySQL);
queryRS = statement.executeQuery();
MyTable myTable = new MyTable();
List key_fields = new ArrayList();
List common_fields = new ArrayList();
//统计主键和普通字段
while(queryRS.next()){
String field_name = queryRS.getString("Field");
//注意：得到的Type可能是varchar(n),也可能是datetime
String sql_type = queryRS.getString("Type");
String key = queryRS.getString("Key");
String commont = queryRS.getString("Commont");
String java_type = getJavaTypeFromSQLType(sql_type);
//设置字段相关信息
MyField field = new MyField();
field.setField_name(field_name);
field.setSql_type(sql_type);
field.setJava_type(java_type);
field.setField_comment(commont);
if(key != null && key.equalsIgnoreCase("pri")){
field.setIs_primary(true);
key_fields.add(field);
}else{
field.setIs_primary(false);
common_fields.add(field);
}
//是否需要导java.math.BigDecimal包
if(java_type.equalsIgnoreCase("bigdecimal"))
myTable.setMath_flag(true);
if(java_type.equalsIgnoreCase("date")||java_type.equalsIgnoreCase("time")||java_type.equalsIgnoreCase("timestamp"))
myTable.setDate_flag(true);
}
//设置表相关的信息
myTable.setTableName(tableName);
myTable.setKey_fields(key_fields);
myTable.setCommon_fields(common_fields);
tables.add(myTable);
}
return tables;
} catch (SQLException e) {
e.printStackTrace();
return tables;
} finally{
try {
if(queryRS != null)
queryRS.close();
if(connectionRS != null)
connectionRS.close();
if(statement != null)
statement.close();
if(connection != null)
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}else{
return tables;
}
}
/**
*
* @param tableName
* @return 返回表名称为 tableName 的表的结构
* @throws Exception
*/
public static MyTable getTable(String tableName){
Connection connection = getConnection();
String sql = "show full columns from " + tableName;
PreparedStatement preparedStatement = null;
ResultSet rs = null;
MyTable myTable = null;
if(connection != null){
try {
preparedStatement = connection.prepareStatement(sql);
rs = preparedStatement.executeQuery();
myTable = new MyTable();
List commonFieldList = new ArrayList();
List keyFieldList = new ArrayList();
//获取表的结构
while(rs.next()){
String field_name = rs.getString("Field");
//注意：得到的Type可能是varchar(n),也可能是datetime
String sql_type = rs.getString("Type");
String key = rs.getString("Key");
String commont = rs.getString("Comment");
String java_type = getJavaTypeFromSQLType(sql_type);
//设置字段相关信息
MyField field = new MyField();
field.setField_name(field_name);
field.setSql_type(sql_type);
field.setJava_type(java_type);
field.setField_comment(commont);
if(key != null && key.equalsIgnoreCase("pri")){
field.setIs_primary(true);
keyFieldList.add(field);
}else{
field.setIs_primary(false);
commonFieldList.add(field);
}
//是否需要导java.math.BigDecimal包
if(java_type.equalsIgnoreCase("bigdecimal"))
myTable.setMath_flag(true);
if(java_type.equalsIgnoreCase("date")||java_type.equalsIgnoreCase("time")||java_type.equalsIgnoreCase("timestamp"))
myTable.setDate_flag(true);
}
myTable.setTableName(tableName);
myTable.setCommon_fields(commonFieldList);
myTable.setKey_fields(keyFieldList);
return myTable;
} catch (SQLException e) {
e.printStackTrace();
return myTable;
} finally{
try {
if(rs != null)
rs.close();
if(preparedStatement != null)
preparedStatement.close();
if(connection != null)
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}else{
return myTable;
}
}
/**
*
* @param sqlType
* @return SQL类型得到java类型
*/
private static String getJavaTypeFromSQLType(String sqlType){
String javaType = null;
int index = sqlType.indexOf("(");
if(index != -1)
sqlType = sqlType.substring(0, index);
if(sqlType.equalsIgnoreCase("VARCHAR")||sqlType.equalsIgnoreCase("CHAR")||sqlType.contains("TEXT"))
javaType = "String";
else if(sqlType.equalsIgnoreCase("NUMERIC")||sqlType.equalsIgnoreCase("DECIMAL"))
javaType = "BigDecimal";
else if(sqlType.equalsIgnoreCase("BIT"))
javaType = "boolean";
else if(sqlType.equalsIgnoreCase("TINYINT"))
javaType = "byte";
else if(sqlType.equalsIgnoreCase("SAMLLINT"))
javaType = "short";
else if(sqlType.equalsIgnoreCase("INTEGER")||sqlType.equalsIgnoreCase("int")||sqlType.equalsIgnoreCase("mediumint"))
javaType = "int";
else if(sqlType.equalsIgnoreCase("BIGINT"))
javaType = "long";
else if(sqlType.equalsIgnoreCase("REAL"))
javaType = "float";
else if(sqlType.equalsIgnoreCase("FLOAT")||sqlType.equalsIgnoreCase("double"))
javaType = "double";
else if(sqlType.equalsIgnoreCase("binary")||sqlType.equalsIgnoreCase("varbinary")||sqlType.equalsIgnoreCase("longvarbinary"))
javaType = "byte[]";
else if(sqlType.equalsIgnoreCase("date"))
javaType = "Date";
else if(sqlType.equalsIgnoreCase("time"))
javaType = "Time";
else if(sqlType.equalsIgnoreCase("datetime")||sqlType.equalsIgnoreCase("timestamp"))
javaType = "Timestamp";
return javaType;
}
/**
*
* @param str
* @return 把一个字符串首字母大写
*/
public static String capitalFirstChar(String str){
if(str == null || str.trim().equals(""))
return str;
else{
char[] charArray = str.toCharArray();
if(charArray[0] >= 'a' && charArray[0] <= 'z'){
charArray[0] = (char) (charArray[0] - 32);
return String.valueOf(charArray);
}
else
return str;
}
}
/**
*
* @param packageName
* @param tableName
* @return 生成实体类，返回一个包含实体类内容的StringBuffer，只需要把这个StringBuffer写到一个.java文件即可
*/
public static StringBuffer generateEntity(String packageName, String tableName){
MyTable myTable = getTable(tableName);
StringBuffer buffer = new StringBuffer();
buffer.append("package ").append(packageName).append(";\r\n");
if(myTable.math_flag)
buffer.append("import java.math.*;\r\n");
if(myTable.date_flag)
buffer.append("import java.util.Date;\r\n");
buffer.append("\r\n");
buffer.append("public class ").append(capitalFirstChar(tableName)).append(" {\r\n");
StringBuffer contentBuffer = generateSetAndGet(myTable);
buffer.append(contentBuffer);
buffer.append("\r\n}");
return buffer;
}
/**
*
* @param myTable
* @return 生成实体类的主体内容，包括属性声明，以及get和set方法
*/
private static StringBuffer generateSetAndGet(MyTable myTable){
StringBuffer buffer = new StringBuffer();
//思想：先生成属性声明，再生成相应的get和set方法
//1.生成字段属性声明
myTable.getCommon_fields().addAll(myTable.getCommon_fields());
for(MyField field : myTable.getCommon_fields()){
String field_name = field.getField_name();
String field_type = field.getJava_type();
buffer.append("\tprivate " + field_type + " " + field_name + ";\r\n");
}
/*//2.生成普通字段属性声明
for(MyField field : myTable.getCommon_fields()){
String field_name = field.getField_name();
String field_type = field.getJava_type();
buffer.append("\tprivate " + field_type + " " + field_name + ";\r\n");
}
//3.生成主键字段属性的getter和setter
for(MyField field : myTable.getKey_fields()){
String field_name = field.getField_name();
String field_type = field.getField_type();
//生成set方法
buffer.append("\tpublic void set" + capitalFirstChar(field_name) + "(" + field_type + " " + field_name + "){\r\n");
buffer.append("\t\tthis.").append(field_name).append(" = ").append(field_name).append(";\r\n");
buffer.append("\t}").append("\r\n");
//生成get方法
buffer.append("\tpublic ").append(field_type).append(" get").append(capitalFirstChar(field_name)).append("(){\r\n");
buffer.append("\t\treturn this.").append(field_name).append(";\r\n");
buffer.append("\t}").append("\r\n");
}*/
//4.生成普通字段属性的getter和setter
for(MyField field : myTable.getCommon_fields()){
String field_name = field.getField_name();
String field_type = field.getJava_type();
//生成set方法
buffer.append("\tpublic void set" + capitalFirstChar(field_name) + "(" + field_type + " " + field_name + "){\r\n");
buffer.append("\t\tthis.").append(field_name).append(" = ").append(field_name).append(";\r\n");
buffer.append("\t}").append("\r\n");
//生成get方法
buffer.append("\tpublic ").append(field_type).append(" get").append(capitalFirstChar(field_name)).append("(){\r\n");
buffer.append("\t\treturn this.").append(field_name).append(";\r\n");
buffer.append("\t}").append("\r\n");
}
return buffer;
}
/**
*
* @param myTable
* @return 主键作为参数时，返回的参数列表:如果主键有多个，那么参数列表就是一个实体类，否则，就是主键所对应的属性字段为参数
*/
private static StringBuffer generatePrimaryKeyParam(MyTable myTable){
StringBuffer buffer = new StringBuffer();
List key_fields = myTable.getKey_fields();
if(key_fields.size() >= 2){
String tableName = myTable.getTableName();
String entityName = capitalFirstChar(tableName);
buffer.append(entityName).append(" ").append(tableName);
}else{
MyField key_field = key_fields.get(0);
String field_type = key_field.getJava_type();
String field_name = key_field.getField_name();
buffer.append(field_type).append(" ").append(field_name);
}
return buffer;
}
/**
*
* @param packageName mapper接口的包名
* @param tableName 生成哪张表的mapper接口
* @return 生成mapper接口，包含下列方法：
* (1)插入一条记录
* (2)查询记录的总数
* (3)根据主键来删除一条记录、根据主键来更新一条记录、根据主键来查询记录
*/
public static StringBuffer generateMapperInterface(String packageName, String tableName){
MyTable myTable = getTable(tableName);
StringBuffer buffer = new StringBuffer();
buffer.append("package ").append(packageName).append(";\r\n");
//import 实体类
buffer.append("import 实体类;").append("\r\n\r\n");
buffer.append("public interface ").append(capitalFirstChar(tableName)).append("Mapper{\r\n");
buffer.append("\r\n");
//插入一条记录
buffer.append("\t");
buffer.append("public void insertRecord(").append(capitalFirstChar(tableName)).append(" ").append(tableName).append(");");
buffer.append("\r\n");
//查询记录的总数
buffer.append("\t");
buffer.append("public int queryRecordCount(").append(")");
buffer.append("\r\n");
//先判断是否存在主键，如果不存在主键，则不生成和主键相关的方法
List key_fields = myTable.getKey_fields();
if(key_fields != null){
//参数列表
StringBuffer params = generatePrimaryKeyParam(myTable);
//根据主键来删除一条记录
buffer.append("\t");
buffer.append("public void deleteByPrimaryKey(");
buffer.append(params);
buffer.append(");");
buffer.append("\r\n");
//根据主键来更新记录
buffer.append("\t");
buffer.append("public void updateByPrimaryKey(");
buffer.append(params);
buffer.append(");");
buffer.append("\r\n");
//根据主键来查询
buffer.append("\t");
buffer.append("public void selectByPrimaryKey(");
buffer.append(params);
buffer.append(");");
buffer.append("\r\n");
}
buffer.append("\r\n}");
return buffer;
}
｝ 生成器类代码
public class MyGenerator {
public static void generate(String basePackageName , String tableName) throws IOException{
String projectPath = System.getProperty("user.dir");
String src_path = projectPath + File.separator + "src";
File file = new File(src_path);
if(basePackageName.indexOf(".") != -1){
String[] packageName_part = basePackageName.split(".");
for(String part : packageName_part){
file = new File(file,part);
if(!file.exists())
file.mkdirs();
}
}else{
file = new File(file , basePackageName);
if(!file.exists())
file.mkdirs();
}
String template_path = projectPath + File.separator + "config" + File.separator + "template" ;
File templateDirtory = new File(template_path);
Configuration configuration = new Configuration();
configuration.setDefaultEncoding("UTF-8");
configuration.setDirectoryForTemplateLoading(templateDirtory);
configuration.setObjectWrapper(new DefaultObjectWrapper());
File[] template_files = templateDirtory.listFiles();
for(File template_file : template_files){
//得到模版文件名xxx.ftl
String file_name = template_file.getName();
int index = file_name.indexOf(".");
String template_name = file_name.substring(0, index);
File target_file_dir = null , target_file = null;
String target_file_name = null;
//如果是po.ftl
if(template_name.equalsIgnoreCase("po")){
target_file_dir = new File(file , "po");
if(!target_file_dir.exists())
target_file_dir.mkdirs();
target_file_name = DataBaseUtil.capitalFirstChar(tableName) + ".java";
}else if(template_name.equalsIgnoreCase("dao")){
//如果是dao.ftl,则生成mapper接口
target_file_dir = new File(file , "mapper");
if(!target_file_dir.exists())
target_file_dir.mkdirs();
target_file_name = DataBaseUtil.capitalFirstChar(tableName) + "Mapper.java";
} else if(template_name.equalsIgnoreCase("mapper")){
//如果是mapper.ftl，则生成mapper.xml
target_file_dir = new File(file , "mapper");
if(!target_file_dir.exists())
target_file_dir.mkdirs();
target_file_name = DataBaseUtil.capitalFirstChar(tableName) + "Mapper.xml";
} else if(template_name.equalsIgnoreCase("service")){
//如果是service.ftl，则生成service接口
target_file_dir = new File(file , "service");
if(!target_file_dir.exists())
target_file_dir.mkdirs();
target_file_name = DataBaseUtil.capitalFirstChar(tableName) + "Service.java";
}else if(template_name.equalsIgnoreCase("serviceImpl")){
//如果是serviceImpl.ftl，则生成service接口实现类
target_file_dir = new File(file , "serviceImpl");
if(!target_file_dir.exists())
target_file_dir.mkdirs();
target_file_name = DataBaseUtil.capitalFirstChar(tableName) + "ServiceImpl.java";
}else if(template_name.equalsIgnoreCase("controller")){
//如果是controller.ftl，则生成controller
target_file_dir = new File(file , "controller");
if(!target_file_dir.exists())
target_file_dir.mkdirs();
target_file_name = DataBaseUtil.capitalFirstChar(tableName) + "Controller.java";
} else if(template_name.equalsIgnoreCase("mybatis")){
//如果是mybatis.ftl，则生成mybatis核心配置文件sqlMapConfig.xml
File config_source_folder = new File(projectPath);
config_source_folder = new File(config_source_folder , "config");
if(!config_source_folder.exists())
config_source_folder.mkdirs();
target_file_dir = new File(config_source_folder , "mybatis");
if(!target_file_dir.exists())
target_file_dir.mkdirs();
target_file_name = "sqlMapConfig.xml";
} else if(template_name.equalsIgnoreCase("spring")){
//如果是spring.ftl，则生成spring核心配置文件spring.xml
File config_source_folder = new File(projectPath);
config_source_folder = new File(config_source_folder , "config");
if(!config_source_folder.exists())
config_source_folder.mkdirs();
target_file_dir = new File(config_source_folder , "spring");
if(!target_file_dir.exists())
target_file_dir.mkdirs();
target_file_name = "spring.xml";
}
target_file = new File(target_file_dir , target_file_name);
if(target_file.exists())
target_file.delete();
target_file.createNewFile();
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(target_file)));
Template template = configuration.getTemplate(file_name);
Map paramMap = new HashMap();
MyTable table = DataBaseUtil.getTable(tableName);
table.setPackage_name_base(basePackageName);
paramMap.put("table", table);
try {
template.process(paramMap, writer);
} catch (TemplateException e) {
e.printStackTrace();
} finally{
if(writer != null)
writer.close();
}
}
}
｝ <#-- 生成实体类 -->
package ${table.package_name_base}.po;
<#if table.date_flag>
import java.util.Date;
<#if table.math_flag>
import java.math.BigDecimal;
public class ${table.tableName?cap_first} {
<#-- 生成字段属性 -->
<#list table.common_fields + table.key_fields as field>
private ${field.java_type} ${field.field_name};
<#-- 生成字段get方法 -->
<#list table.common_fields + table.key_fields as field>
public ${field.java_type} get${field.field_name?cap_first}(){
return this.${field.field_name};
}
<#-- 生成字段set方法 -->
<#list table.common_fields + table.key_fields as field>
public void set${field.field_name?cap_first}(${field.java_type} ${field.field_name}){
this.${field.field_name} = ${field.field_name};
}
<#-- 生成mapper.xml映射文件,这里使用的mybatis版本是3.2.2 -->
<#-- 查询表中记录的条数 -->
<#-- 生成插入记录的方法 -->
insert into ${table.tableName}
<#list (table.common_fields + table.key_fields) as field>
<#if field_index == 0>
(${field.field_name}
<#elseif field_index == ((table.common_fields + table.key_fields)?size -1)>
,${field.field_name})
<#else>
,${field.field_name}
values
<#list (table.common_fields + table.key_fields) as field>
<#if field_index ==0>
(${"#"}{${field.field_name}},
<#elseif field_index == ((table.common_fields + table.key_fields)?size -1)>
,${"#"}{${field.field_name}})
<#else>
,${"#"}{${field.field_name}}
<#if table.key_fields?size != 0>
<#-- 主键只有一个时 -->
<#if table.key_fields?size == 1>
update ${table.tableName} set
<#list table.common_fields as field>
<#if field_index == (table.common_fields?size -1)>
${field.field_name} = ${"#"}{${field.field_name}}
<#else>
${field.field_name} = ${"#"}{${field.field_name}},
where ${table.key_fields[0].field_name} = ${"#"}{${table.key_fields[0].field_name}}
<#else>
update ${table.tableName} set
<#list table.common_fields as field>
<#if field_index = (table.common_fields?size -1)>
${field.field_name} = ${"#"}{${field.field_name}}
<#else>
${field.field_name} = ${"#"}{${field.field_name}},
where
<#list table.key_fields as field>
<#if field_index = (table.key_fields?size -1)>
${field.field_name} = ${"#"}{${field.field_name}}
<#else>
${field.field_name} = ${"#"}{${field.field_name}} and
${table.key_fields[0].field_name} = ${"#"}{${table.key_fields[0].field_name}}
执行代码生成器之前的项目结构
执行代码生成器，会看到效果（有错误是因为我没有导入相关的jar包）
代码写得有点简单，没有什么技术点，但是能够让我在以后的学习和工作中减少不必要的无休止的写po类，增删改查这些让人头疼的事。
如果过程中有什么错误或是不足，请指出，谢谢。