希望代码足以描述关键点，但如果您有任何进一步的问题，请发表评论：

<?php

class WPSE_Submit_From_Front {
    const NONCE_VALUE = \'front_end_new_post\';
    const NONCE_FIELD = \'fenp_nonce\';

    protected $pluginPath;
    protected $pluginUrl;
    protected $errors = array();
    protected $data = array();

    function __construct() {
        $this->pluginPath = plugin_dir_path( __file__ );
        $this->pluginUrl  = plugins_url( \'\', __file__ );

        add_action( \'wp_enqueue_scripts\', array( $this, \'addStyles\' ) );
        add_shortcode( \'post_from_front\', array( $this, \'shortcode\' ) );

        // Listen for the form submit & process before headers output
        add_action( \'template_redirect\',  array( $this, \'handleForm\' ) );
    }

    function addStyles() {
        wp_enqueue_style( \'submitform-style\', "$this->pluginUrl/submitfromfront.css" );
    }

    /**
     * Shortcodes should return data, NOT echo it.
     *
     * @return string
     */
    function shortcode() {
        if ( ! current_user_can( \'publish_posts\' ) )
            return sprintf( \'<p>Please <a href="%s">login</a> to post links.</p>\', esc_url( wp_login_url(  get_permalink() ) ) );
        elseif ( $this->isFormSuccess() )
            return \'<p class="success">Nice one, post created.</p>\';
        else
            return $this->getForm();
    }

    /**
     * Process the form and redirect if sucessful.
     */
    function handleForm() {
        if ( ! $this->isFormSubmitted() )
            return false;

        // http://php.net/manual/en/function.filter-input-array.php
        $data = filter_input_array( INPUT_POST, array(
            \'postTitle\'   => FILTER_DEFAULT,
            \'location2\'   => FILTER_DEFAULT,
            \'postContent\' => FILTER_DEFAULT,
        ));

        $data = wp_unslash( $data );
        $data = array_map( \'trim\', $data );

        // You might also want to more aggressively sanitize these fields
        // By default WordPress will handle it pretty well, based on the current user\'s "unfiltered_html" capability

        $data[\'postTitle\']   = sanitize_text_field( $data[\'postTitle\'] );
        $data[\'location2\']   = sanitize_text_field( $data[\'location2\'] );
        $data[\'postContent\'] = wp_check_invalid_utf8( $data[\'postContent\'] );

        $this->data = $data;

        if ( ! $this->isNonceValid() )
            $this->errors[] = \'Security check failed, please try again.\';

        if ( ! $data[\'postTitle\'] )
            $this->errors[] = \'Please enter a title.\';

        if ( ! $data[\'postContent\'] )
            $this->errors[] = \'Please enter the content.\';

        if ( ! $this->errors ) {
            $post_id = wp_insert_post( array(
                \'post_title\'   => $data[\'postTitle\'],
                \'post_content\' => $data[\'postContent\'],
                \'post_status\'  => \'publish\',
            ));

            if ( $post_id ) {
                add_post_meta( $post_id, \'location2\', $data[\'location2\'] );

                // Redirect to avoid duplicate form submissions
                wp_redirect( add_query_arg( \'success\', \'true\' ) );
                exit;

            } else {
                $this->errors[] = \'Whoops, please try again.\';
            }
        }
    }

    /**
     * Use output buffering to *return* the form HTML, not echo it.
     *
     * @return string
     */
    function getForm() {
        ob_start();
        ?>

<div id ="frontpostform">
    <?php foreach ( $this->errors as $error ) : ?>

        <p class="error"><?php echo $error ?></p>

    <?php endforeach ?>

    <form id="formpost" method="post">
        <fieldset>
            <label for="postTitle">Post Title</label>
            <input type="text" name="postTitle" id="postTitle" value="<?php

                // "Sticky" field, will keep value from last POST if there were errors
                if ( isset( $this->data[\'postTitle\'] ) )
                    echo esc_attr( $this->data[\'postTitle\'] );

            ?>" />
        </fieldset>

        <fieldset>
            <label for="postContent">Content</label>
            <textarea name="postContent" id="postContent" rows="10" cols="35" ><?php

                if ( isset( $this->data[\'postContent\'] ) )
                    echo esc_textarea( $this->data[\'postContent\'] );

            ?></textarea>
        </fieldset>

        <fieldset>
            <button type="submit" name="submitForm" >Create Post</button>
        </fieldset>

        <?php wp_nonce_field( self::NONCE_VALUE , self::NONCE_FIELD ) ?>
    </form>
</div>

        <?php
        return ob_get_clean();
    }

    /**
     * Has the form been submitted?
     *
     * @return bool
     */
    function isFormSubmitted() {
        return isset( $_POST[\'submitForm\'] );
    }

    /**
     * Has the form been successfully processed?
     *
     * @return bool
     */
    function isFormSuccess() {
        return filter_input( INPUT_GET, \'success\' ) === \'true\';
    }

    /**
     * Is the nonce field valid?
     *
     * @return bool
     */
    function isNonceValid() {
        return isset( $_POST[ self::NONCE_FIELD ] ) && wp_verify_nonce( $_POST[ self::NONCE_FIELD ], self::NONCE_VALUE );
    }
}

new WPSE_Submit_From_Front;