DBGenerator：获取PO注解信息生成表sql
2016-08-16 23:22
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开发过程中，常常创建了PO之后，还要去数据库里创建对应的表，相似的过程，却要做两次，有没有感觉很麻烦？使用Hibernate可以生成表，还要去配置，而且无法得到表创建sql，于是 DBGenerator 应运而生了。DBGenerator是一个工具类，能获取PO类的注解信息，自动生成表创建SQL，节省了很多时间，同时也能保证测试环境和生产环境表的一致性。
hibernate3.jar
founded in class["+clazz.getName()+"]");
}
Table table = (Table)clazz.getAnnotation(Table.class);
String tableName = table.name();
StringBuilder sb = new StringBuilder("-- Create table\n");
sb.append("create table " + tableName + "\n");
sb.append("(\n");
Field[] fieldArr = clazz.getDeclaredFields();
int maxLength = getMaxLength(clazz, fieldArr);
String primaryKey = generateFields(clazz, sb, fieldArr, maxLength);
sb.append(");\n");
generatePrimaryKey(sb, tableName, primaryKey);
return sb.toString();
}
/**
* 生成sql字段
* @param clazz
* @param sb
* @param fieldArr
* @param primaryKey
* @param maxLength
* @return
*/
private String generateFields(Class clazz, StringBuilder sb,
Field[] fieldArr, int maxLength) {
String primaryKey = "";
Field field;
for(int i=0;i<fieldArr.length;i++){
field = fieldArr[i];
int offset;
try {
PropertyDescriptor pd = new PropertyDescriptor(field.getName(), clazz);
Method mt = pd.getReadMethod();
if(null != mt){
Column col = (Column)mt.getAnnotation(Column.class);
writeBlankSpace(sb, 2);
sb.append(col.name());
offset = maxLength - col.name().length();
writeBlankSpace(sb, offset);
writeBlankSpace(sb, 1);
sb.append(convertJava2Oracle(field, col));
if(mt.isAnnotationPresent(Id.class)){
sb.append(" not null");
primaryKey = col.name();
}
}
} catch (IntrospectionException e) {
//找不到readMethod,跳过
//throw new RuntimeException("No " + field.getName() + "'s ReadMethod founded in class["+clazz.getName()+"]");
continue;
}
if(i != (fieldArr.length -1)){
sb.append(",");
}
sb.append("\n");
}
return primaryKey;
}
/**
* 生成主键sql
* @param tableName
* @param sb
* @param primaryKey
*/
private void generatePrimaryKey(StringBuilder sb, String tableName, String primaryKey) {
if(StringUtils.isNotBlank(primaryKey)){
sb.append("alter table " + tableName + "\n");
sb.append(" add primary key (" + primaryKey + ")\n");
sb.append(" using index;");
}
}
/**
* 获得Field最大长度
* @param clazz
* @param fieldArr
*/
private int getMaxLength(Class clazz, Field[] fieldArr) {
Field field;
int maxLength = 0;
for(int i=0;i<fieldArr.length;i++){
field = fieldArr[i];
PropertyDescriptor pd;
try {
pd = new PropertyDescriptor(field.getName(), clazz);
Method mt = pd.getReadMethod();
if(null != mt){
if(!mt.isAnnotationPresent(Column.class)){
throw new RuntimeException("No Annotation[Column] founded in Method["+mt.getName()+"]");
}
Column col = (Column)mt.getAnnotation(Column.class);
int temLength = col.name().length();
if(temLength > maxLength){
maxLength = temLength;
}
}
} catch (IntrospectionException e) {
//找不到readMethod,跳过
//throw new RuntimeException("No " + field.getName() + "'s ReadMethod founded in class["+clazz.getName()+"]");
continue;
}
}
return maxLength;
}
/**
*
* 将java类型转换为orable类型
* @param field
* @param col
* @return
*/
private String convertJava2Oracle(Field field, Column col){
//TODO 此处可根据自己需要做类型转换
String type = "VARCHAR2";
if(field.getType().equals(String.class)){
type = "VARCHAR2(" + col.length() + ")";
}else if(field.getType().equals(java.util.Date.class) || field.getType().equals(java.sql.Date.class)){
type = "DATE";
}else if(field.getType().equals(Integer.class)){
type = "NUMBER";
}
return type;
}
/**
*
* 输出空格
* @param sb
* @param n
*/
private void writeBlankSpace(StringBuilder sb, int n){
for(int i=0;i<n;i++){
sb.append(" ");
}
}
}
1. jar包依赖
commons-lang-2.6.jarhibernate3.jar
2. 源码
package com.cg.db;
import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import javax.persistence.Column;
import javax.persistence.Id;
import javax.persistence.Table;
import org.apache.commons.lang.StringUtils;
import com.sun.xml.internal.bind.v2.model.core.ID;
/**
*
* <p>根据PO生成表创建sql<p>
* <p>根据read方法上的注解，生成数据库字段信息，没有read方法的Field跳过<p>
* @since jdk1.6
* @date 2016-8-15
*/
public class DBGenerator {
/**
*
* 根据类的注解信息生成表sql
* @param clazz
* @return
*/
public String generate(Class clazz){
if(!clazz.isAnnotationPresent(Table.class)){
throw new RuntimeException("No Annotation