  (Abridged) In this paper, multi-wavelength data are compiled for a sample of
1425 Fermi blazars to calculate their spectral energy distributions (SEDs). A
parabolic function, $\log(\nu F_{\nu}) = P_1(\log\nu - P_2)^2 + P_3,$ is used
for SED fitting. Synchrotron peak frequency ($\log \nu_p$), spectral curvature
($P_1$), peak flux ($\nu_{\rm p}F_{\rm \nu_p}$), and integrated flux ($\nu
F_{\nu}$) are successfully obtained for 1392 blazars (461 flat spectrum radio
quasars-FSRQs, 620 BL Lacs-BLs and 311 blazars of uncertain type-BCUs, 999
sources have known redshifts). Monochromatic luminosity at radio 1.4 GHz,
optical R band, X-ray at 1 keV and $\gamma$-ray at 1 GeV, peak luminosity,
integrated luminosity and effective spectral indexes of radio to optical
($\alpha_{\rm RO}$), and optical to X-ray ($\alpha_{\rm OX}$) are calculated.
The "Bayesian classification" is employed to log$\nu_{\rm p}$ in the rest frame
for 999 blazars with available redshift and the results show that 3 components
are enough to fit the $\log\nu_{\rm p}$ distribution, there is no ultra high
peaked subclass. Based on the 3 components, the subclasses of blazars using the
acronyms of Abdo et al. (2010a) are classified, and some mutual correlations
are also studied. Conclusions are finally drawn as follows: (1) SEDs are
successfully obtained for 1392 blazars. The fitted peak frequencies are
compared with common sources from samples available (Sambruna et al. 1996,
Nieppola et al. 2006, 2008, Abdo et al. 2010a). (2) Blazars are classified as
low synchrotron peak sources (LSPs) if $\log\nu_{\rm p}$(Hz) $\leq 14.0$,
intermediate synchrotron peak sources (ISPs) if $14.0 < \log\nu_{\rm p}$(Hz)
$\leq 15.3$, and high synchrotron peak sources (HSPs) if $\log\nu_{\rm p}$(Hz)
$> 15.3$. (3) $\gamma$-ray emissions are strongly correlated with radio
emissions. (...)
