本文详细介绍了数据库操作方法及实体类设计规范，包括插入、更新、删除操作，以及属性注解的应用。
package com.core.annotation;import static java.lang.annotation.elementtype.type;import static java.lang.annotation.retentionpolicy.runtime;import java.lang.annotation.retention;import java.lang.annotation.target;/** * @author zy * @version 创建时间：jul 2, 2010 2:39:20 pm */@target({type})@retention(runtime)public @interface table { public abstract string name() default ""; public abstract string catalog() default ""; public abstract string schema() default ""; }package com.core.annotation;import static java.lang.annotation.elementtype.field;import static java.lang.annotation.elementtype.method;import static java.lang.annotation.retentionpolicy.runtime;import java.lang.annotation.retention;import java.lang.annotation.target;/** * @author zy * @version 创建时间：jul 2, 2010 2:54:28 pm */@target({field,method})@retention(runtime)public @interface column { public abstract string name() default ""; public abstract boolean unique() default false; public abstract boolean nullable() default true; public abstract string type() default "string"; public abstract string definition() default ""; public abstract int length() default 32; }package com.entity;import java.io.serializable;import com.core.annotation.column;import com.core.annotation.table;/** * @author zy * @version 创建时间：jul 6, 2010 9:15:18 am */@table(name="t_user")public class user implements serializable{ private static final long serialversionuid = 6602217772155966261l; string id; string name; string sex; @column(name="user_name") public string getname() { return name; } public void setname(string name) { this.name = name; } @column(name="sex") public string getsex() { return sex; } public void setsex(string sex) { this.sex = sex; } public string getid() { return id; } public void setid(string id) { this.id = id; }}package com.core.util;import java.io.serializable;import java.lang.reflect.invocationtargetexception;import java.lang.reflect.method;import com.entity.user;import com.core.annotation.column;import com.core.annotation.table;/** * @author zy * @version 创建时间：jul 2, 2010 2:00:55 pm */public class annotationutil { @suppresswarnings("unchecked") public static string save(user u){ string temp = null; stringbuffer sb = new stringbuffer(); string id = string.valueof(u.getid()); if(id == null || id.trim().equals("")){ stringbuffer key = new stringbuffer(); stringbuffer value = new stringbuffer(); sb.append("insert into "); class c = u.getclass(); object [] obj = null; if(c != null && c.isannotationpresent(table.class)){ table table = (table) c.getannotation(table.class); try { temp = table.name(); if(temp.trim().equals("")){ sb.append(c.getname().trim()); }else{ sb.append(temp.trim()); } } catch (exception e) { sb.append(c.getname().trim()); } }else{ sb.append(c.getname().trim()); } method [] method = u.getclass().getdeclaredmethods(); for(method m : method){ if(m != null && m.isannotationpresent(column.class)){ column column = m.getannotation(column.class); temp = column.name(); if(temp.trim().equals("")){ key.append(m.getname().substring(3).trim()).append(","); }else{ key.append(temp.trim()).append(","); } try { temp = string.valueof(m.invoke(u, obj)); value.append("'").append(temp.trim()).append("',"); } catch (illegalargumentexception e) { e.printstacktrace(); value.append("'',"); } catch (illegalaccessexception e) { e.printstacktrace(); value.append("'',"); } catch (invocationtargetexception e) { e.printstacktrace(); value.append("'',"); } } } key.deletecharat(key.lastindexof(",")); value.deletecharat(value.lastindexof(",")); sb.append(" (").append(key).append(") values"); sb.append(" (").append(value).append(")"); }else{ sb.append("update "); class c = u.getclass(); object [] obj = null; if(c != null && c.isannotationpresent(table.class)){ table table = (table) c.getannotation(table.class); try { temp = table.name(); if(temp.trim().equals("")){ sb.append(c.getname().trim()); }else{ sb.append(temp.trim()); } } catch (exception e) { sb.append(c.getname().trim()); } }else{ sb.append(c.getname().trim()); } sb.append(" set "); method [] method = u.getclass().getdeclaredmethods(); for(method m : method){ if(m != null && m.isannotationpresent(column.class)){ column column = m.getannotation(column.class); temp = column.name(); if(temp.trim().equals("")){ sb.append(m.getname().substring(3).trim()).append("="); try { temp = string.valueof(m.invoke(u, obj)); sb.append("'").append(temp.trim()).append("',"); } catch (illegalargumentexception e) { e.printstacktrace(); sb.append("'',"); } catch (illegalaccessexception e) { e.printstacktrace(); sb.append("'',"); } catch (invocationtargetexception e) { e.printstacktrace(); sb.append("'',"); } }else{ sb.append(temp.trim()).append("="); try { temp = string.valueof(m.invoke(u, obj)); sb.append("'").append(temp.trim()).append("',"); } catch (illegalargumentexception e) { e.printstacktrace(); sb.append("'',"); } catch (illegalaccessexception e) { e.printstacktrace(); sb.append("'',"); } catch (invocationtargetexception e) { e.printstacktrace(); sb.append("'',"); } } } } sb.deletecharat(sb.lastindexof(",")); sb.append(" where id='").append(id.trim()).append("'"); } return sb.tostring(); } @suppresswarnings("unchecked") public static string delete(user u,serializable id){ string temp = null; stringbuffer sb = new stringbuffer("delete from "); class c = u.getclass(); if(c != null && c.isannotationpresent(table.class)){ table table = (table)c.getannotation(table.class); try { temp = table.name(); if(temp.trim().equals("")){ sb.append(c.getname().trim()); }else{ sb.append(temp.trim()); } } catch (exception e) { sb.append(c.getname().trim()); } }else{ sb.append(c.getname().trim()); } sb.append(" where id='").append(string.valueof(id)).append("'"); return sb.tostring(); } @suppresswarnings("unchecked") public static void main(string[] args) { user user = new user(); user.setid("234"); user.setname("历史"); user.setsex("男"); system.out.println(save(user)); system.out.println(delete(user,"123")); }}
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