使用JNDI操作LDAP（2）

好了，现在介绍一些简单的操作。

l         修改属性

修改属性包括增加，修改，删除属性。

修改一个对象的属性的方法之一就是提供一个修改请求列表(ModificationItem)。每个ModificationItem由一定数量的指定修改类型的常量（ADD_ATTRIBUTE,REPLACE_ATTRIBUTE,REMOVE_ATTRIBUTE）以及修改的属性Attribute组成。

下面是我写的简单的操作代码：

    /**

     * updates the specified extension information,including add,replace,remove attribute

     * @param search_base The search distinguishedName.

     * @param mod_op The modificational operation,can use ADD_ATTRIBUTE,REPLACE_ATTRIBUTE,REMOVE_ATTRIBUTE.

     * @param ctx The ldapcontext.

     */

    public static void updateAttribute(String search_base,int mod_op,LdapContext ctx){

        try {

            Attributes attrs = null;

            Attribute attr = null;           

            //define ModificationItem

            ModificationItem[] mods =new ModificationItem[1];

           

            //operate the ModificationItem

            switch(mod_op){

                //operation add_attribute

                case LdapContext.ADD_ATTRIBUTE:{

                    //instance an attribute to be added

                    attr = new BasicAttribute("description");

                    //value of attribute description to add

                    attr.add("I add an attribute.");

                    //instance ModificationItem

                    mods[0] = new ModificationItem(LdapContext.ADD_ATTRIBUTE,attr);

                    //add description attribute

                  ctx.modifyAttributes(search_base,mods);

                    attrs = ctx.getAttributes(search_base,new String[]{"description"});

                    //print the value of new attribute

                    System.out.println("****new attribute****");

                    System.out.println("attribute: description ");

                    System.out.println("value:"+attrs.get("description"));                   

                    break;

                }

               

                //operation replace_attribute

                case LdapContext.REPLACE_ATTRIBUTE:{

                    //print the value of original attribute

                    attrs = ctx.getAttributes(search_base,new String[]{"description"});                   

                    System.out.println("****original attribute****");

                    System.out.println("attribute:description");

                    System.out.println("value:"+attrs.get("description"));

                    //instance an attribute to be replaced

                    attr = new BasicAttribute("description");

                    //add value of attribute description to replace

                    attr.add("I replace an attribute.");

                    //instance ModificationItem

                   mods[0] = new ModificationItem(LdapContext.REPLACE_ATTRIBUTE,attr);

                    //replace description attribute                   

                    ctx.modifyAttributes(search_base,mods);

                    attrs = ctx.getAttributes(search_base,new String[]{"description"});

                    //print the value of replaced attribute

                    System.out.println("****replaced attribute****");

                    System.out.println("attribute:description");

                    System.out.println("value:"+attrs.get("description"));

                    break;

                }

               

                //operation remove_attribute

                case LdapContext.REMOVE_ATTRIBUTE:{

                    //print the value of original attribute

                    attrs = ctx.getAttributes(search_base,new String[]{"description"});                   

                    System.out.println("****original attribute****");

                    System.out.println("attribute:description");

                    System.out.println("value:"+attrs.get("description"));

                    //instance an attribute to be removed

                    attr = new BasicAttribute("description");

                    //instance ModificationItem

                    mods[0] = new ModificationItem(LdapContext.REMOVE_ATTRIBUTE,attr);

                    //remove description attribute                   

                    ctx.modifyAttributes(search_base,mods);

                    attrs = ctx.getAttributes(search_base,new String[]{"description"});

                    //print the value of removed attribute

                    System.out.println("****removed attribute****");

                    System.out.println("attribute:description");

                    System.out.println("value:"+attrs.get("description"));

                    break;

                }

            }           

        } catch (Exception e){

            System.out.println(e.toString());

        }       

    }

这个例子里面有注释，而且很好懂，我就不一一详解了。

要注意的是，ModificationItem[]数组可以指定一系列的操作，修改的顺序和它们出现在数组中的顺序一致，要么所有的修改都完成，要么一个都不完成，即一个修改操作是一个事务。