Simple Local Avatars 是英文的，只有一个主文件 simple-local-avatars.php，你也可以将这个功能直接集成到你的主题中，只需将该插件的 simple-local-avatars.php 放到正在使用的主题的根目录，然后在 functions.php文件中使用下面的代码引入该文件即可：

require_once(TEMPLATEPATH . '/simple-local-avatars.php');

通过以上的两种方式，你的网站已经具备了自定义用户头像功能。那么，如何调用自定义头像？很简单，可以调用get_simple_local_avatar 或 get_avatar 函数即可，例如：

<?php echo get_avatar(get_the_author_meta('ID')); ?>

注：如果你已设置了Gravatar头像，也上传了自定义头像，优先显示自定义头像

修改上传头像文件的目录

以下是 simple-local-avatars.php 文件，找到：

$avatar = wp_handle_upload( $_FILES['simple-local-avatar'], array( 'mimes' => $mimes, 'test_form' => false, 'unique_filename_callback' => array( $this, 'unique_filename_callback' ) ) );

修改成：（即在上传文件之前加入upload_dir 过滤器）

add_filter( 'upload_dir', 'avatar_upload_dir' );
$avatar = wp_handle_upload( $_FILES['simple-local-avatar'], array( 'mimes' => $mimes, 'test_form' => false, 'unique_filename_callback' => array( $this, 'unique_filename_callback' ) ) );
remove_filter( 'upload_dir', 'avatar_upload_dir' );

然后在functions.php中加入：avatar_upload_dir函数

function avatar_upload_dir( $dir ) {
return array(
'path' => $dir['basedir'] . '/avatars',
'url' => $dir['baseurl'] . '/avatars',
'subdir' => '/avatars',
) + $dir;
}

完整的 simple-local-avatars.php

<?php
/**
* add field to user profiles
*/

class Simple_Local_Avatars {
private $user_id_being_edited;

public function __construct() {
add_filter( 'get_avatar', array( $this, 'get_avatar' ), 10, 5 );

add_action( 'admin_init', array( $this, 'admin_init' ) );

add_action( 'show_user_profile', array( $this, 'edit_user_profile' ) );
add_action( 'edit_user_profile', array( $this, 'edit_user_profile' ) );

add_action( 'personal_options_update', array( $this, 'edit_user_profile_update' ) );
add_action( 'edit_user_profile_update', array( $this, 'edit_user_profile_update' ) );

add_filter( 'avatar_defaults', array( $this, 'avatar_defaults' ) );
}

public function get_avatar( $avatar = '', $id_or_email, $size = 96, $default = '', $alt = false ) {

if ( is_numeric($id_or_email) )
$user_id = (int) $id_or_email;
elseif ( is_string( $id_or_email ) && ( $user = get_user_by( 'email', $id_or_email ) ) )
$user_id = $user->ID;
elseif ( is_object( $id_or_email ) && ! empty( $id_or_email->user_id ) )
$user_id = (int) $id_or_email->user_id;

if ( empty( $user_id ) )
return $avatar;

$local_avatars = get_user_meta( $user_id, 'simple_local_avatar', true );

if ( empty( $local_avatars ) || empty( $local_avatars['full'] ) )
return $avatar;

$size = (int) $size;

if ( empty( $alt ) )
$alt = get_the_author_meta( 'display_name', $user_id );

// generate a new size
if ( empty( $local_avatars[$size] ) ) {
$upload_path = wp_upload_dir();
$avatar_full_path = str_replace( $upload_path['baseurl'], $upload_path['basedir'], $local_avatars['full'] );
$image_sized = image_resize( $avatar_full_path, $size, $size, true );
// deal with original being >= to original image (or lack of sizing ability)
$local_avatars[$size] = is_wp_error($image_sized) ? $local_avatars[$size] = $local_avatars['full'] : str_replace( $upload_path['basedir'], $upload_path['baseurl'], $image_sized );
// save updated avatar sizes
update_user_meta( $user_id, 'simple_local_avatar', $local_avatars );
} elseif ( substr( $local_avatars[$size], 0, 4 ) != 'http' ) {
$local_avatars[$size] = home_url( $local_avatars[$size] );
}

$author_class = is_author( $user_id ) ? ' current-author' : '' ;
$avatar = "<img alt='" . esc_attr( $alt ) . "' src='" . $local_avatars[$size] . "' class='avatar avatar-{$size}{$author_class} photo' height='{$size}' width='{$size}' />";

return apply_filters( 'simple_local_avatar', $avatar );
}

public function admin_init() {
//load_plugin_textdomain( 'simple-local-avatars', false, dirname( plugin_basename( __FILE__ ) ) . '/localization/' );

register_setting( 'discussion', 'simple_local_avatars_caps', array( $this, 'sanitize_options' ) );
add_settings_field( 'simple-local-avatars-caps', __('上传头像权限','simple-local-avatars'), array( $this, 'avatar_settings_field' ), 'discussion', 'avatars' );
}

public function sanitize_options( $input ) {
$new_input['simple_local_avatars_caps'] = empty( $input['simple_local_avatars_caps'] ) ? 0 : 1;
return $new_input;
}

public function avatar_settings_field( $args ) {
$options = get_option('simple_local_avatars_caps');

echo '
<label for="simple_local_avatars_caps">
<input type="checkbox" name="simple_local_avatars_caps" id="simple_local_avatars_caps" value="1" ' . @checked( $options['simple_local_avatars_caps'], 1, false ) . ' />
' . __('仅具有头像上传权限的用户具有设置本地头像权限（作者及更高等级角色）。','simple-local-avatars') . '
</label>
';
}

public function edit_user_profile( $profileuser ) {
?>
<h3><?php _e( '头像','simple-local-avatars' ); ?></h3>

<table class="form-table">
<tr>
<th><label for="simple-local-avatar"><?php _e('上传头像','simple-local-avatars'); ?></label></th>
<td style="width: 50px;" valign="top">
<?php echo get_avatar( $profileuser->ID ); ?>
</td>
<td>
<?php
$options = get_option('simple_local_avatars_caps');

if ( empty($options['simple_local_avatars_caps']) || current_user_can('upload_files') ) {
do_action( 'simple_local_avatar_notices' );
wp_nonce_field( 'simple_local_avatar_nonce', '_simple_local_avatar_nonce', false );
?>
<input type="file" name="simple-local-avatar" id="simple-local-avatar" /><br />
<?php
if ( empty( $profileuser->simple_local_avatar ) )
echo '<span class="description">' . __('尚未设置本地头像，请点击“浏览”按钮上传本地头像。','simple-local-avatars') . '</span>';
else
echo '
<input type="checkbox" name="simple-local-avatar-erase" value="1" /> ' . __('移除本地头像','simple-local-avatars') . '<br />
<span class="description">' . __('如需要修改本地头像，请重新上传新头像。如需要移除本地头像，请选中上方的“移除本地头像”复选框并更新个人资料即可。<br/>移除本地头像后，将恢复使用 Gravatar 头像。','simple-local-avatars') . '</span>
';
} else {
if ( empty( $profileuser->simple_local_avatar ) )
echo '<span class="description">' . __('尚未设置本地头像，请在 Gravatar.com 网站设置头像。','simple-local-avatars') . '</span>';
else
echo '<span class="description">' . __('你没有头像上传权限，如需要修改本地头像，请联系站点管理员。','simple-local-avatars') . '</span>';
}
?>
</td>
</tr>
</table>
<script type="text/javascript">var form = document.getElementById('your-profile');form.encoding = 'multipart/form-data';form.setAttribute('enctype', 'multipart/form-data');</script>
<?php
}

public function edit_user_profile_update( $user_id ) {
if ( ! isset( $_POST['_simple_local_avatar_nonce'] ) || ! wp_verify_nonce( $_POST['_simple_local_avatar_nonce'], 'simple_local_avatar_nonce' ) ) //security
return;

if ( ! empty( $_FILES['simple-local-avatar']['name'] ) ) {
$mimes = array(
'jpg|jpeg|jpe' => 'image/jpeg',
'gif' => 'image/gif',
'png' => 'image/png',
'bmp' => 'image/bmp',
'tif|tiff' => 'image/tiff'
);

// front end (theme my profile etc) support
if ( ! function_exists( 'wp_handle_upload' ) )
require_once( ABSPATH . 'wp-admin/includes/file.php' );

$this->avatar_delete( $user_id ); // delete old images if successful

// need to be more secure since low privelege users can upload
if ( strstr( $_FILES['simple-local-avatar']['name'], '.php' ) )
wp_die('For security reasons, the extension ".php" cannot be in your file name.');

$this->user_id_being_edited = $user_id; // make user_id known to unique_filename_callback function

// Register our path override.
add_filter( 'upload_dir', 'avatar_upload_dir' );

$avatar = wp_handle_upload( $_FILES['simple-local-avatar'], array( 'mimes' => $mimes, 'test_form' => false, 'unique_filename_callback' => array( $this, 'unique_filename_callback' ) ) );
// Set everything back to normal.
remove_filter( 'upload_dir', 'avatar_upload_dir' );

if ( empty($avatar['file']) ) { // handle failures
switch ( $avatar['error'] ) {
case 'File type does not meet security guidelines. Try another.' :
add_action( 'user_profile_update_errors', create_function('$a','$a->add("avatar_error",__("请上传有效的图片文件。","simple-local-avatars"));') );
break;
default :
add_action( 'user_profile_update_errors', create_function('$a','$a->add("avatar_error","<strong>".__("上传头像过程中出现以下错误：","simple-local-avatars")."</strong> ' . esc_attr( $avatar['error'] ) . '");') );
}

return;
}

update_user_meta( $user_id, 'simple_local_avatar', array( 'full' => $avatar['url'] ) ); // save user information (overwriting old)
} elseif ( ! empty( $_POST['simple-local-avatar-erase'] ) ) {
$this->avatar_delete( $user_id );
}
}

/**
* remove the custom get_avatar hook for the default avatar list output on options-discussion.php
*/
public function avatar_defaults( $avatar_defaults ) {
remove_action( 'get_avatar', array( $this, 'get_avatar' ) );
return $avatar_defaults;
}

/**
* delete avatars based on user_id
*/
public function avatar_delete( $user_id ) {
$old_avatars = get_user_meta( $user_id, 'simple_local_avatar', true );
$upload_path = wp_upload_dir();

if ( is_array($old_avatars) ) {
foreach ($old_avatars as $old_avatar ) {
$old_avatar_path = str_replace( $upload_path['baseurl'], $upload_path['basedir'], $old_avatar );
@unlink( $old_avatar_path );
}
}

delete_user_meta( $user_id, 'simple_local_avatar' );
}

public function unique_filename_callback( $dir, $name, $ext ) {
$user = get_user_by( 'id', (int) $this->user_id_being_edited );
$name = $base_name = sanitize_file_name( $user->user_login . '_avatar' );
$number = 1;

while ( file_exists( $dir . "/$name$ext" ) ) {
$name = $base_name . '_' . $number;
$number++;
}

return $name . $ext;
}
}

$simple_local_avatars = new Simple_Local_Avatars;

/**
* more efficient to call simple local avatar directly in theme and avoid gravatar setup
*
* @param int|string|object $id_or_email A user ID, email address, or comment object
* @param int $size Size of the avatar image
* @param string $default URL to a default image to use if no avatar is available
* @param string $alt Alternate text to use in image tag. Defaults to blank
* @return string <img> tag for the user's avatar
*/
function get_simple_local_avatar( $id_or_email, $size = '96', $default = '', $alt = false ) {
global $simple_local_avatars;
$avatar = $simple_local_avatars->get_avatar( '', $id_or_email, $size, $default, $alt );

if ( empty ( $avatar ) )
$avatar = get_avatar( $id_or_email, $size, $default, $alt );

return $avatar;
}